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5 Clues That a Partner Could Become Unfaithful

New research adds to our understanding of repeat infidelity.

"Tempted by the fruit of another
Tempted but the truth is discovered
What's been going on
Now that you have gone"
— "Tempted," Squeeze

"Writers are always writing about infidelity. It's so dramatic. The wickedness of it, the secrecy, the complications, the finding that you thought you were one person but you're also this other person. The innocent life and the guilty life." — Alice Munro

Once a Cheater, Always a Cheater?

Source: gpointstudio/Shutterstock

In their paper in the Archives of Sexual Behavior, Knopp and colleagues review the literature on infidelity and report their recent work looking at predictors for having affairs (Knopp et al., 2017). They note that despite a growing body of research, there is scant data about the role of prior affairs in predicting infidelity over time. They were primarily interested in the factors underlying serial infidelity, and understanding to what degree infidelity in one relationship predicted infidelity in the next.

Anecdotally, this is what we see—when someone has been unfaithful in the past, they are more likely to be unfaithful again. I've often observed that people who engage in infidelity frequently experienced infidelity in their parents' relationship. While I haven't seen any data on this, it makes sense as familiarity with a behavior in general makes it more likely to do that behavior, via social learning and modeling. This holds true for many other behaviors, where past personal history and family behavior partially predicts individual behavior, including aggression and suicide—though it is worth noting that such history is not 100 percent predictive, and many with the risk factor do not go on to repeat the behavior.

Of course, infidelity is an area rife with conflict and differing perspectives. In an environment in which having multiple partners is a social norm, infidelity, if it exists at all in romantic relationships, may take on different meanings. The individuals involved may react differently and only experience infidelity if context-specific norms are violated, resulting in betrayal. In cultures where monogamy is the norm, emotional and sexual infidelity are likely to be deemed transgressive—moral, religious, social, and possibly legal transgressions, with ensuing consequences. Infidelity often involves deliberately manipulative and deceitful behaviors, acting like one person and, in some cases, later on being revealed as someone else.

This can be a deeply unsettling, disorienting experience, making especially the one being deceived, but also the one being unfaithful, come to doubt their own ability to know who they can trust. It can strike at the heart of identity, making us become unfamiliar to ourselves and one another. Doubt and confusion may influence subsequent relationship choices, since a sadly common story is that people thought they could trust the person, only to find out they were again wrong—and often it seems that loyal people are seen as untrustworthy, when they are not. Trust radar ("trustdar"?) appears to be thrown off by betrayal, and in my opinion and experience, this often starts young.

Can We Agree to Disagree?

In mixed societies, societies like ours with turbulent eddies of changing and clashing values and norms, infidelity is likely to be multilayered, requiring a complex balance among many perspectives—if a balance is even achievable or desirable. Some folks believe in strict monogamy, others are in "open relationships" or may sexually identify as inherently polygamous, pansexual, asexual, and so on. In any event, judgment is one main axis around which the debate revolves—those who judge and how they judge, and those who do not judge, and how they engage in discourse. Common ground can be hard to find, and the intense emotions surrounding infidelity often lead to polarization.

The researchers here acknowledge that infidelity is difficult to study due to variations in definitions of what infidelity is, along with related terms, "such as infidelity, unfaithfulness, cheating, extra-marital or extra-relational affairs, extra-dyadic involvement, and extra-dyadic sexual involvement are commonly used in the literature ... they all attempt to assess the same underlying construct, which we refer to as infidelity."

The note that—in spite of changes in norms for intimate romantic relationships—the majority of couples expect monogamy. Nevertheless, infidelity is common, with a yearly incidence of 2 to 4 percent for both men and women, as noted in this recent post on research about what prevents couples from cheating. The lifetime rate of infidelity is estimated at 20 percent for married couples. Infidelity harms both people in the couple, the people around them, including the paramour, as well as children and other friends and family who are bystanders to the betrayal. Infidelity is often experienced as betrayal trauma, and represents a serious and damaging breach of trust for the majority of couples, as well as a form of painful rejection.

What Factors Are Associated With Infidelity?

Included in the many consequences of infidelity are strain on the relationship, often leading to splitting up. Infidelity is one of the most commonly reported precursors to divorce, and one of the most thorny and intractable problems couples therapists face in their work.

Risk factors for infidelity from prior research include:

1. Low relationship commitment.

2. Declining sexual and relationship satisfaction.

3. Specific personality traits (e.g., avoidant attachment style; extroversion, neuroticism, and lower agreeableness, in terms of the "Big 5" personality traits).

4. Permissive attitudes about sex/infidelity.

5. Being in a social context that approves of infidelity.

Regarding serial infidelity, Knopp and colleagues point to two major theories, though the literature on infidelity in general is rich, complex, and growing: how many high-quality alternative partners are available; and attitudes about whether infidelity is acceptable.

From these perspectives, the following general factors are most relevant:

1. When people know people who are appealing and available, they are more likely to succumb to temptation.

2. People who have already had affairs know that they exist, and can happen.

3. People who already have had an affair are more likely to find infidelity acceptable in the first place (for whatever reasons—social, upbringing, personality, etc.).

4. People who engage in infidelity are more likely convince themselves affairs are acceptable in order to lower cognitive dissonance (a form of inner conflict).

5. Therefore, having an affair may make partners more likely to have another affair, as efforts to alleviate cognitive dissonance may result in a shift toward greater acceptance of infidelity in order to integrate unfaithful behavior into one's view of oneself.

6. For some, unfaithful behavior may lead them to address underlying issues and alter their behavior and beliefs and again come to find infidelity to be unacceptable.

But it is not just "cheater" factors that may predict serial infidelity. There are partner factors as well. For instance, there are folks who tend to date people who have had prior affairs, or who are already in relationships. They are more likely to pick a partner who is generally untrustworthy, and often also unavailable. When we date someone knowing they have cheated in the past, we want assurance that it won't happen again, and typically want to know what happened before getting too close.

Sometimes, the other person is hiding their affair history, and they either are waiting for the right time to share it, or we find out from someone else. The relationship is founded on a serious deception, but we are already attached and want to believe the best, and we want to avoid loss and have the relationship succeed. While this can work out, sometimes we end up fooling ourselves and regretting it. When relationships start out so intense, and people bond so hard and fast, it's easy to get involved before we find out who we're dating.

Take "serial monogamy," for example. How many serial monogamists begin the relationship with the next person before the old relationship has worn off, or ended? Not everyone, but it is pretty common. Sometimes, both people are still involved with someone else and coming off of the last relationship, but a lot of the time it's one or the other—and there have gotta be lots of reasons for that, which we can't go into here, but which have been extensively studied elsewhere.

In addition, they report that if you've had an affair, you may be more likely to be suspicious that partners will be unfaithful. Such a suspicion is often toxic to relationships, leading to unfounded jealously, mistrust, negative feelings, and reminding participants of past bad relationships. And it gets hard to tell exactly what is real and what is not real, because without trust, all communication becomes suspect and meaning unreliable. Affairs, after all, typically involved protracted periods of deceit, misdirection, concealment, and omission.

Research on Recurring Infidelity

In "Once a Cheater, Always a Cheater? Serial Infidelity Across Subsequent Relationships," Knopp and co-authors choose to define "infidelity" by "ESI"—or "extra-dyadic sexual involvement." They acknowledge how what "sexual" is can vary, and that it misses some behaviors, such as kissing (possibly) and emotional affairs. In addition, they note that ESI may include people who permit sexual relations with others, but who do not consider that to be infidelity, though they note their sample had less than 2 percent of participants reporting being in an "open relationship". They recruited subjects from a large pool of people involved in the study of romantic relationships. They are from around the U.S., in unmarried romantic relationships for at least two months, and included a sample of 484 participants who completed surveys 3 to 4 times per year, completing at least 10 out of the total of 11 surveys sent out over about a five-year period. Their sample had 329 women and 155 men, covered a range of ethnicities, ranging in age from 15 to 35, with on average 1.6 relationships, but ranging from 1 to 7 over the study period.

They asked participants about ESI each time: "Have you had sexual relations with someone other than your partner since you began serious dating?" and rated their responses, no, yes with one person, and yes with more than one person—44 percent overall reported their own engagement in ESI.

Thirty-eight percent reported known ESI by a partner, and 18 percent reported suspected ESI. They pooled data on demographic factors, using logistic regression to seek correlations among the data. One question asked was whether ESI in an earlier relationship predicted ESI in a later relationship, whether people who suspected ESI were more likely to suspect ESI in a later relationship, and so on.

Overall, they found people were more likely to have longer first relationships than second relationships, 38.8 months versus 29.6, and a greater proportion of people in their first relationship lived together, 65 percent versus 19 percent. ESI was lower on all measures in more highly educated respondents, and suspicion of ESI was higher in older and unemployed participants. Gender and income level was not associated with ESI.

In terms of ESI associations, those who reported their own ESI in the first relationship were 3.4 times more likely (34 percent) to report ESI in the second relationship (18 percent) than those who did not report ESI in the first relationship.

Known and suspected ESI were also associated over sequential relationships. Partners who reported known ESI in the first relationship were 2.4 times more likely (22 percent) to report it in the second relationship (9 percent). Likewise, partners who suspected ESI in the first relationship were 4.3 times more likely (37 percent) to suspect it in the second (6 percent). There was no association between engaging in ESI in the first relationship and higher reporting of either known or suspected ESI in the second. There was no correlation between gender or age in ESI between first and second relationships. This was a younger, less often married population, which may account for higher overall rates of ESI compared to other reports, as well as the specific findings related to educational background and gender, which have also not been found uniformly.

Regardless of the modest correlation between past and future ESI, the majority did not report infidelity. Understanding what factors predict the over three-fold risk for infidelity repeaters was not measured by this study, and is an area for future investigation. Determining these factors will be important for understanding how infidelity works in romantic relationships, and to both identify risky situations (and make different choices) as well as to guide areas of personal focus for those who wish to avoid repeating infidelity—for both "cheaters" and "cheatees."

It is interesting that participating in ESI was not associated with partner ESI in future relationships, going against the intuitive expectation that cheaters would be mistrustful of others. However, people who were suspicious of ESI continued to be so, suggesting individual personality factors.

Importantly, people who knew that their first partners engaged in ESI were twice as likely to report ESI in the next relationship, supporting the idea, but unable to prove causality, that some people tend to date cheaters. Given the possibility of developmental issues related to various forms of neglect, coming from homes with impaired parental relationships and (possibly related) personality and attachment factors, it will be useful to look at potential causal relationships in more detail, as well.

Further Thoughts

For now we can only conclude that some correlation exists, and make an informed guess that there is a chance that infidelity in one relationship does not cause someone to pick someone unfaithful the next time, but rather both choices are influenced by underlying factors related to how one perceives oneself and others, and makes decisions about intimacy choices. Regardless, there is plenty to say about tending to pick bad love objects, and interest in how to make better choices. It's strange, because even when people try their hardest to find someone better, we seem too often to trick ourselves and end up with someone who is (at least in some ways) all too familiar.

Although "the heart has its reasons which reason knows nothing of ... We know the truth not only by the reason, but by the heart" (Pascal), it makes sense to proceed with caution when considering forming a serious relationship—especially as we are considering taking emotional risks and making emotional investments when there are red flags. Be open in asking about attitudes about infidelity and looking for and discussing risk factors for infidelity—including the individual traits and relationship factors described above, as well as the presence of a history of infidelity. If we tend to date people who cheat on us, though, it's a good idea to slow down with relationships and sort out what's going on there.

Early on in relationships, we can be blinded by feelings of passionate love and fantasies of perfect union, making us miss obvious areas of concern and putting us unnecessarily in harm's way. But being overly cautious can close off opportunities to grow closer to people with whom we could have very fulfilling relationships. I find it helpful to remember that trust is not a goal and is not black-and-white—trust is a process which grows over time, and applies to different relationships in different ways. Regardless, we should feel safe with people close to us ... but not so safe that our relationships are too restricted.

Please send questions, topics or themes you'd like me to try and address in future blogs, via my PT bio page.

Twitter: @GrantHBrennerMD



Knopp, K., Scott, S., Ritchie, L., Rhoades, G. K., Markman, H. J., Stanley, S. M. (2017). Once a Cheater, Always a Cheater? Serial Infidelity Across Subsequent Relationships. Archives of Sexual Behavior, 7 August. DOI 10.1007/s10508-017-1018-1