ICERT Press

1. Introduction

Romantic infidelity — a violation of an agreed-upon standard of sexual or emotional exclusivity — is one of the most commonly cited precipitants of relationship distress and dissolution (Blow & Hartnett, 2005). Population-based estimates suggest that between roughly 13% and 40% of individuals engage in some form of infidelity over the course of their romantic lives (as cited in Mitchell et al., 2025). While a substantial literature has examined why people engage in infidelity, empirical attention to the psychological experience of the betrayed partner has developed more slowly, and research on how that partner navigates the decision to end or preserve the relationship remains comparatively sparse.

Over roughly the last two decades, clinicians and, increasingly, empirical researchers have used the term Post-Infidelity Stress Disorder (PISD) — sometimes framed instead as infidelity-related post-traumatic stress — to describe a cluster of trauma-like symptoms reported by betrayed partners: intrusive and repetitive thoughts about the discovery, hypervigilant monitoring of the partner, emotional numbing alternating with acute distress, and disrupted sleep and concentration (Ortman, 2009). Unlike many popularized clinical terms, this one has attracted a genuine empirical literature: several peer-reviewed studies have now used standardized trauma measures to demonstrate that a substantial proportion of betrayed partners meet or approach clinical thresholds for probable PTSD following infidelity discovery (Dean & Bergner, 2018; Roos et al., 2019).

A second, complementary framework for understanding the betrayed partner’s experience is ambiguous loss theory, developed by Pauline Boss to describe grief that lacks the clarity and social validation of a conventional loss (Boss & Carnes, 2012). In the context of infidelity, the betrayed partner frequently experiences the unfaithful partner as simultaneously present and absent: physically still there, but psychologically transformed in the betrayed partner’s perception. Because the relationship has not necessarily ended, this loss receives little of the social sanction, ritual, or sympathy ordinarily available to the bereaved (Boss & Yeats, 2014).

This paper synthesizes the empirical and theoretical literature on both of these dimensions — trauma-like symptomatology and ambiguous, disenfranchised grief — and examines how they jointly shape betrayed partners’ decision-making about the future of the relationship. Rather than reporting new primary data, this review integrates findings from published quantitative, qualitative, and grounded-theory studies to build a composite account of the betrayed partner’s psychological experience and to identify where the existing evidence base remains thin.

2. Objectives of the Review

• To synthesize existing empirical evidence on the prevalence, symptomatology, and correlates of post-infidelity traumatic stress (PISD).

• To examine how ambiguous loss theory has been, and can be, applied to the betrayed partner’s experience of a partner who remains physically present but psychologically altered.

• To synthesize qualitative and grounded-theory findings on the cognitive and emotional processes underlying betrayed partners’ decisions to remain in or terminate the relationship.

• To integrate betrayal trauma theory, ambiguous loss theory, and commitment/investment theory into a single conceptual model of the post-infidelity decision-making process.

• To identify gaps in the existing literature and generate recommendations for clinical practice and future empirical research.

3. Guiding Review Questions and Theoretical Propositions

As an integrative review rather than a primary empirical study, this paper is organized around review questions and theory-derived propositions that are evaluated against the published literature, rather than statistically tested hypotheses.

• RQ1: What proportion of betrayed partners exhibit symptoms consistent with post-infidelity traumatic stress, and how severe are these symptoms relative to established clinical thresholds?

• RQ2: How does the concept of ambiguous loss map onto betrayed partners’ documented experience of a partner who remains physically present after infidelity?

• RQ3: What psychological and relational factors do existing qualitative studies identify as central to betrayed partners’ decisions to stay or leave?

• RQ4: How, if at all, does the decision-making process change over time across the studies reviewed?

Proposition 1 (trauma severity and dependence): Consistent with betrayal trauma theory, the literature is expected to show that psychological injury is more severe when the betrayed partner reports high pre-existing dependence on the relationship (Freyd, 1996; Gómez & Freyd, 2019).

Proposition 2 (ambiguous loss and prolonged grief): Consistent with ambiguous loss theory, studies capturing betrayed partners’ own language are expected to reveal descriptions of grief without closure, and an absence of social recognition for that grief, distinguishing it from bereavement following a definitive loss (Boss & Carnes, 2012).

Proposition 3 (investment and decisional ambivalence): Consistent with the investment model of commitment, betrayed partners reporting greater investment (time, shared property, children) are expected to describe more prolonged decisional ambivalence, independent of the severity of trauma symptoms (Rusbult et al., 1998).

4. Literature Review

4.1 Infidelity as a Relational and Psychological Trauma

Couple therapy literature has long identified infidelity as one of the most damaging and difficult presenting problems in clinical practice (as cited in Mitchell et al., 2025). Documented consequences for betrayed partners include depression, anxiety, post-traumatic stress symptoms, diminished self-worth, and poorer long-term physical health outcomes (Cano & O’Leary, 2000; as cited in Fife et al., 2026). Kachadourian et al. (2015), studying combat-exposed U.S. service members, found that those who reported infidelity experienced significantly higher post-traumatic stress symptom severity and depression than those who did not, extending evidence of infidelity’s psychological impact beyond civilian samples.

4.2 Empirical Evidence for Post-Infidelity Traumatic Stress (PISD)

Several quantitative studies now provide direct empirical support for the informally termed PISD construct. Dean and Bergner (2018) developed the Infidelity Discovery Reaction Scale (IDRS) based on qualitative themes drawn from women’s accounts of discovering a partner’s infidelity, and found that IDRS scores correlated positively with scores on the PTSD Checklist (PCL); participants’ mean PCL score (M = 54.02) substantially exceeded the established civilian clinical cutoff of 45, indicating that on average the sample was experiencing considerable trauma symptomatology. Roos, O’Connor, Canevello, and Bennett (2019), in a sample of 73 unmarried young adults who had experienced a partner’s infidelity, found that 45.2% met criteria for probable infidelity-related PTSD after controlling for gender, race, and prior Criterion A trauma exposure; infidelity-related PTSD symptoms were significantly associated with depressive symptoms, and post-traumatic cognitions partially or fully mediated associations with depression, perceived stress, and anxiety. Other studies report even higher rates in specific populations: Steffens and Rennie (2006) found that 69.6% of a sample of women partnered with sex addicts met PTSD diagnostic criteria following disclosure, while estimates elsewhere in the literature range from approximately one-third to 60% of women meeting significant PTSD symptomology after partner infidelity, depending on sample and measurement approach (Laaser et al., 2017; Özgün, 2010, as cited in Partner Betrayal Trauma Validation literature). Shrout and Weigel (2018) further demonstrated that betrayed partners’ cognitive appraisals of the infidelity were associated with both mental health outcomes and health-compromising behaviors in the aftermath of discovery, underscoring that the psychological impact of infidelity extends into physical health-relevant behavior.

Taken together, this quantitative literature substantiates the clinical concept of PISD: although it remains outside formal DSM-5-TR nosology because infidelity does not meet the Criterion A definition of a traumatic stressor, the empirical symptom profile of betrayed partners across multiple independent samples closely resembles that of diagnosable PTSD (Roos et al., 2019; Dean & Bergner, 2018).

4.3 Betrayal Trauma Theory

Betrayal trauma theory, introduced by Jennifer Freyd, explains why betrayal by a close, depended-upon figure produces more severe psychological harm than harm inflicted by a stranger, proposing that injury severity is proportional to the degree of dependence on the betrayer (Freyd, 1996). Freyd’s related concept of betrayal blindness describes the ways individuals may unconsciously minimize or fail to register signs of betrayal to preserve a relationship on which they depend (Gómez & Freyd, 2019). Subsequent research has linked betrayal trauma to elevated shame and dissociation, particularly when the betrayal originates from a high-closeness figure such as a romantic partner (Platt et al., 2017).

4.4 Ambiguous Loss and Disenfranchised Grief

Pauline Boss’s concept of ambiguous loss describes a loss that remains unclear, unresolved, and often unrecognized by others (Boss & Yeats, 2014). Boss distinguished physical ambiguous loss (a person physically absent but psychologically present) from psychological ambiguous loss (a person physically present but psychologically absent or altered), the latter of which maps closely onto betrayed partners’ commonly reported sense that the unfaithful partner is simultaneously familiar and no longer fully knowable (Boss & Yeats, 2014). Because the relationship has not necessarily ended, this loss receives none of the social sanction or ritual typically afforded to bereavement — a pattern consistent with the broader construct of disenfranchised grief. Boss and Carnes (2012) argue that ambiguous loss resists closure altogether, and that therapeutic goals should shift from achieving resolution toward building tolerance for paradox and enduring, livable uncertainty. Although ambiguous loss theory has been applied extensively to missing-person, dementia, and chronic-illness contexts, its direct application to infidelity remains comparatively rare in the empirical literature, representing a conceptual bridge this review draws explicitly.

4.5 Decision-Making: Commitment, Investment, and Cognitive Dissonance

Rusbult’s investment model proposes that commitment is a function of satisfaction, the quality of perceived alternatives, and the size of prior investment (Rusbult et al., 1998), with investment functioning as a switching cost that increases commitment independently of current satisfaction (Rusbult & Martz, 1995). Drigotas, Safstrom, and Gentilia (1999) applied the model directly to infidelity, finding that pre-existing commitment levels predicted subsequent infidelity and, by extension, that lower post-betrayal commitment is associated with a higher likelihood of dissolution. Cognitive dissonance theory (Festinger, 1957) offers a complementary account of the discomfort betrayed partners describe when reconciling continued love for a partner with knowledge of that partner’s betrayal — a tension capable of producing simultaneous approach and avoidance impulses toward the same relationship.

4.6 Qualitative and Grounded-Theory Research on Betrayed Partners

A growing body of qualitative research has examined betrayed partners’ experiences directly. Yaghoobi Tourki, Khodabakhshi-Koolaee, and Falsafinejad (2022), using grounded theory with married individuals in Tehran, identified a staged process of psychological reaction and coping following disclosure of marital infidelity, describing the discovery itself as a genuinely traumatic event capable of endangering the marriage. Butler (2025), in a phenomenological dissertation study of women discovering long-term partners’ infidelity, found that all participants developed PTSD-like symptoms following discovery, that suspicion beforehand did not lessen the impact of confirmed discovery, and that participants frequently assumed inappropriate personal responsibility for their partners’ infidelity — a finding consistent with betrayal trauma theory’s account of self-blame as a defensive response to dependence on the betrayer.

Fife and colleagues have produced a linked program of grounded-theory research on infidelity recovery. Fife, Theobald, Gossner, Yakum, and White (2022) interviewed 22 emerging adults no longer with the partner who betrayed them, identifying a four-stage healing process spanning emotional, relational, and personal dimensions. A companion study examined couples who remained together, describing the joint relational work required for healing following disclosure (Fife et al., 2023), and a further study extended this program of research to examine infidelity decision-making specifically among emerging adult women (Fife et al., 2026). On the side of the partner who was unfaithful, Perez (2023) used grounded theory with 13 men to describe infidelity as the product of a continuous process of justification and rationalization spanning the pre-affair context, escalation (‘snowballing’), motivated reasoning, and the post-affair decision itself — a useful counterpoint that situates the betrayed partner’s experience within the broader relational system.

Most directly relevant to the present review, Mitchell, Brown, Spencer, and Harris (2025) conducted semi-structured interviews with 11 injured partners who had already chosen to remain with their partner after infidelity, identifying nine central themes: stance on infidelity, sharing with others, reasons to stay, apology, social support, sexual intimacy expectations, rebuilding trust, therapy, and other resources. A related earlier study by Mitchell and colleagues (2022) compared the experiences of injured and involved partners directly, finding both overlapping and divergent recovery processes between the two roles. Because Mitchell et al.’s (2025) sample consisted specifically of partners who had already decided to stay, the earlier, more ambivalent decision-making window — when staying and leaving both remain live possibilities — is comparatively underexamined in this otherwise rich literature.

5. Research Gap

This review identifies three persistent gaps in the literature. First, although quantitative studies (Dean & Bergner, 2018; Roos et al., 2019) have empirically substantiated the trauma-like symptom profile associated with PISD, no validated, infidelity-specific clinical measure has achieved widespread adoption; researchers continue to rely on general-purpose PTSD checklists validated for other traumatic stressors, and PISD remains outside formal diagnostic nosology because infidelity does not meet the DSM-5 Criterion A definition of a traumatic stressor (Trauma Care, 2023).

Second, while ambiguous loss theory is well established in bereavement, chronic illness, and missing-person contexts (Boss & Carnes, 2012; Boss & Yeats, 2014), it has been comparatively underused as an explicit interpretive framework for infidelity, despite a strong conceptual fit between the theory’s core claims and betrayed partners’ commonly reported sense of a partner who is present yet altered. Few of the qualitative studies reviewed here (e.g., Yaghoobi Tourki et al., 2022; Butler, 2025) explicitly invoke ambiguous loss as a framework, even though their reported themes — confusion, prolonged non-linear grief, absence of social recognition — align closely with it.

Third, existing qualitative and grounded-theory studies have tended to sample either partners who have already decided to stay (Mitchell et al., 2025) or partners whose relationships have already ended (Fife et al., 2022), leaving the more psychologically volatile decision-making window — the period of active ambivalence in which staying and leaving both remain live possibilities — comparatively unexamined. No study identified in this review specifically recruits betrayed partners who remain actively undecided at the time of data collection, meaning that current knowledge of the decision-making process is drawn largely from retrospective accounts rather than accounts collected during the period of ambivalence itself.

6. Methodology of the Review

6.1 Review Design

This paper adopts an integrative literature review design, appropriate for synthesizing evidence across quantitative, qualitative, and theoretical sources addressing a common phenomenon (Whittemore & Knafl, 2005). An integrative design was selected over a narrower systematic review because the aim was to combine disparate methodological traditions — psychometric trauma research, grounded theory, phenomenology, and clinical theory — into a single coherent account, rather than to aggregate effect sizes across methodologically homogeneous studies.

6.2 Search Strategy

Literature was identified through structured searches of academic databases and search engines (including sources indexed via PubMed, Wiley Online Library, SAGE Journals, ResearchGate, and ProQuest Dissertations) using combinations of the following terms: infidelity, betrayal, post-infidelity stress disorder, PISD, betrayal trauma, ambiguous loss, affair recovery, decision-making, investment model, and post-traumatic stress. Searches were supplemented by examining the reference lists of key retrieved articles (a snowball or ancestry approach) to identify additional relevant sources not captured by keyword searches alone.

6.3 Inclusion and Exclusion Criteria

• Included: peer-reviewed journal articles, dissertations, and recognized clinical texts published in English that empirically or theoretically address the psychological experience of the betrayed partner following romantic infidelity.

• Included: studies employing quantitative (survey, psychometric), qualitative (phenomenological, grounded theory), or theoretical/conceptual designs, provided they directly address trauma symptomatology, grief, or decision-making in the context of infidelity.

• Excluded: sources addressing infidelity only tangentially (e.g., general relationship satisfaction research with no infidelity-specific analysis) or sources with no identifiable authorship or peer review pathway (e.g., anonymous blog content), except were used solely to corroborate clinical terminology already established elsewhere in the peer-reviewed literature.

6.4 Synthesis Approach

Retrieved sources were organized thematically around the review’s guiding questions (trauma symptomatology, ambiguous loss, and decision-making) rather than chronologically or by methodology alone. Within each theme, quantitative findings are reported with specific statistics were available, and qualitative/grounded-theory findings are synthesized narratively, consistent with conventions for integrative and narrative reviews in the family and clinical psychology literature (Whittemore & Knafl, 2005).

7. Findings and Results

This section synthesizes the substantive findings reported across the reviewed literature, organized into the same five domains used to structure the review.

7.1 Prevalence and Severity of Post-Infidelity Traumatic Stress

Quantitative findings converge on the conclusion that a substantial minority to majority of betrayed partners experience clinically significant trauma symptoms following discovery. Roos et al. (2019) reported that 45.2% of unmarried young adults who experienced a partner’s infidelity met criteria for probable infidelity-related PTSD, with symptom severity significantly predicting depressive symptoms. Dean and Bergner (2018) found sample-average PCL trauma scores (M = 54.02) well above the clinical severity cutoff of 45. Higher estimates have been reported in more specific clinical populations, including 69.6% meeting PTSD criteria among women whose partners disclosed sexual addiction (Steffens & Rennie, 2006) and a broader estimated range of roughly one-third to 60% across other samples (Laaser et al., 2017; Özgün, 2010). Kachadourian et al. (2015) extended this pattern to a military sample, finding elevated post-traumatic stress and depression symptom severity among combat-exposed service members who reported experiencing a partner’s infidelity.

7.2 Ambiguous Loss and Disenfranchised Grief

Although few studies apply Boss’s framework explicitly, qualitative findings consistently describe a pattern consistent with ambiguous loss. Butler’s (2025) phenomenological interviews found that women described the discovery of infidelity as reshaping their perception of their partner and of themselves in ways that persisted well beyond the discovery event itself, with participants describing the betrayal as a life-defining moment that damaged their capacity to trust and feel safe. Yaghoobi Tourki et al. (2022) similarly identified prolonged, staged psychological reactions to disclosure that did not resolve quickly or linearly, consistent with the non-linear, closure-resistant grief that ambiguous loss theory predicts (Boss & Carnes, 2012).

7.3 Decisional Ambivalence and the Stay-or-Leave Process

Grounded-theory findings converge on a picture of decision-making as gradual and recursive rather than singular. Mitchell et al. (2025) found that injured partners who ultimately stayed described a multi-themed process involving their initial stance on infidelity, reasons for staying, expectations around apology and rebuilding trust, and reliance on therapy and social support — themes that collectively suggest an extended negotiation rather than a single decision point. Fife et al.’s (2022) study of emerging adults whose relationships ended after infidelity identified a four-stage healing process unfolding across emotional, relational, and personal dimensions, indicating that even the decision to leave is followed by an extended psychological process rather than a discrete endpoint. Perez (2023) found that unfaithful partners themselves described their own decision-making as a continuous process of justification, escalation, and motivated reasoning — evidence that the relational context surrounding the betrayed partner’s decision is itself dynamic and evolving, not fixed at the moment of discovery.

7.4 Relational and Identity Renegotiation

For partners who remain together, Mitchell et al. (2025) documented renegotiated expectations around transparency and sexual intimacy, together with an evolving personal narrative about self-worth and judgment. Butler (2025) similarly found that betrayed partners often revised their sense of self and their general capacity to trust others, beyond the immediate relationship, indicating that identity renegotiation extends past the couple system itself.

7.5 Coping and Support

Across the reviewed qualitative studies, informal social support, individual or couple therapy, and religious or spiritual coping consistently emerge as central resources shaping recovery trajectories (Mitchell et al., 2025; Fife et al., 2023). Shrout and Weigel (2018) additionally found that betrayed partners’ cognitive appraisals of the infidelity were linked not only to mental health outcomes but to health-compromising behaviors, suggesting that coping resources and appraisal style shape not just psychological but behavioral and physical health trajectories after betrayal.

8. Discussion

The reviewed literature supports an integrated account of the betrayed partner’s post-infidelity experience that draws jointly on betrayal trauma theory and ambiguous loss theory. Quantitative studies substantiate the trauma-like severity of the betrayed partner’s symptom profile (Dean & Bergner, 2018; Roos et al., 2019), lending empirical weight to the informally used PISD construct even though it remains outside formal diagnostic nosology. At the same time, qualitative and grounded-theory findings reveal a form of grief that does not resolve in the way conventional bereavement does, consistent with Boss’s description of ambiguous, closure-resistant loss (Boss & Carnes, 2012; Butler, 2025; Yaghoobi Tourki et al., 2022).

The decision-making literature (Fife et al., 2022, 2023, 2026; Mitchell et al., 2025; Perez, 2023) consistently portrays the stay-or-leave decision as a gradual, recursive process rather than a single rational calculation, a pattern well explained by the interaction of trauma symptoms (which push toward avoidance and self-protection), ambiguous loss (which resists resolution and prolongs the decision window), and investment-based commitment (which anchors betrayed partners to the relationship independent of current satisfaction) (Rusbult et al., 1998). This three-part interaction offers a plausible integrated explanation for why betrayed partners so often describe the post-discovery period as psychologically exhausting and indeterminate, even when the practical facts of the situation (what happened, with whom, for how long) are already fully known.

Clinically, this integration suggests that interventions drawing solely on trauma-processing techniques may address intrusive symptoms without addressing the unresolved, ambiguous nature of the ongoing relationship, while interventions drawing solely on communication or grief-focused models may underestimate the trauma-like intensity of the betrayed partner’s symptoms. A combined, attachment-informed approach — addressing both symptom reduction and tolerance of ambiguity — appears best matched to the dual nature of the injury described across this literature (Boss & Carnes, 2012; Fife et al., 2023).

This review also has limitations. As an integrative rather than systematic review, formal risk-of-bias assessment and exhaustive database coverage (e.g., full PRISMA methodology) were not applied, and the included quantitative studies vary considerably in sample composition (e.g., unmarried young adults versus clinical samples of partners of sex addicts), limiting direct comparability of prevalence estimates. Several sources are dissertations or non-peer-reviewed clinical writing rather than peer-reviewed empirical articles, and were included specifically to capture clinical consensus around the PISD construct where the peer-reviewed empirical base remains thin.

9. Conclusion and Recommendations

Infidelity produces a well-documented, trauma-like psychological injury in betrayed partners, substantiated across multiple independent quantitative studies using standardized measures (Dean & Bergner, 2018; Roos et al., 2019; Steffens & Rennie, 2006). This injury is compounded by a distinctive, socially unrecognized form of grief for a partner who remains physically present but psychologically altered, consistent with ambiguous loss theory (Boss & Carnes, 2012). Together, these dynamics help explain why the decision to remain in or leave the relationship is so often experienced as a prolonged, recursive process rather than a single choice, a pattern well documented across the grounded-theory and phenomenological literature reviewed here (Fife et al., 2022, 2023; Mitchell et al., 2025; Perez, 2023).

9.1 Recommendations for Clinical Practice

• Clinicians working with betrayed partners should screen explicitly for trauma-like symptoms (intrusive thoughts, hypervigilance, avoidance) using validated instruments, rather than assuming presentation will resemble ordinary relationship distress or grief alone.

• Therapeutic language should explicitly validate the ambiguous, unresolved nature of the loss, helping betrayed partners tolerate uncertainty rather than being pushed prematurely toward a stay-or-leave decision.

• Couple therapists should distinguish between interventions aimed at rebuilding trust (relevant once a decision to stay has been made) and interventions aimed at supporting decisional clarity (relevant during the ambivalent period), as these require different therapeutic goals and pacing.

• Individual therapy alongside any couple work should be considered, given the trauma-specific symptoms betrayed partners may carry independently of the relationship’s eventual outcome.

9.2 Recommendations for Future Research

• Development and validation of a standardized, infidelity-specific traumatic stress measure — building on early instruments such as the Infidelity Discovery Reaction Scale (Dean & Bergner, 2018) — would allow more direct comparison of prevalence estimates across studies.

• Future qualitative and grounded-theory studies should prioritize recruitment of betrayed partners who are still in the active decision-making window, rather than sampling exclusively from those who have already stayed (Mitchell et al., 2025) or already left (Fife et al., 2022).

• Ambiguous loss theory should be applied more explicitly and systematically to infidelity research, given the strong conceptual overlap already visible, if unlabeled, in existing qualitative findings (Butler, 2025; Yaghoobi Tourki et al., 2022).

• Longitudinal designs following betrayed partners over the months following disclosure would help clarify how trauma symptoms, grief, and decisional ambivalence change over time and in response to therapy.

• Comparative research examining betrayed partners across relationship structures (married versus dating; varied gender and orientation compositions) would help clarify how far the patterns identified in this review generalize across populations.