Is a Partner Who Has Cheated Likely to Cheat Again?

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If someone cheats on their partner in one relationship, what are the odds they will do so in another relationship? That’s the question addressed in a new study published in the Archives of Sexual Behavior[i], titled “Once a Cheater, Always a Cheater?: Serial Infidelity Across Subsequent Relationships.” The researchers found that those who were unfaithful in one relationship had three times the odds of being unfaithful in the next, when compared to those who had not been unfaithful in the first relationship.

This research was conducted by a team from our lab at the University of Denver; the study was headed up by Kayla Knopp along with colleagues Shelby Scott, Lane Ritchie, Galena Rhoades, Howard Markman, and myself. It used our national sample of individuals, first recruited when aged 18 to 34, who were in unmarried, serious romantic relationships.[ii] Thus, while most of the literature on infidelity focuses on marriage, this new study focused on those mostly at premarital stages. That is one of the advances from this work, but not the only one. The other is that the sample and methods allowed for assessing infidelity across two relationships within the context of this longitudinal sample that followed individuals for five years, focusing on their romantic relationships.

Historical Findings

There is extensive literature on infidelity in married relationships, with a growing literature on what is often called extra-dyadic sexual involvement (ESI) in unmarried relationships. The literature on infidelity inside and outside of marriage is well summarized in the new paper. I will describe a few highlights here.[iii]

An overwhelming majority of people have the expectation of fidelity of sexual and, often, emotional connection in their monogamous relationships. That is especially obvious in marriage, but it’s also true in serious, unmarried relationships. (There have always been some who seek “open” relationships, in which the partners agree that it is okay to have sex outside the relationship under some conditions, but that is not very common.)

While the lifetime risks for infidelity in marriage have generally run around 20 percent,[iv] the rates of sex with someone outside a current relationship are much higher among those who are unmarried.[v] This should not be shocking since both the norms around fidelity as well as average commitment levels are higher on average for marriage than for other relationships. The possibility of fidelity is simply not as high for those who have not settled down to make a long-term (or lifetime) commitment to a particular partner. Nevertheless, while people may not have committed to another for the long haul, they do tend to expect faithfulness.[vi]

Knopp and colleagues note some of the most common risk factors for infidelity based on prior research. Those include:

• Low commitment to the present relationship
• Low or declining relationship satisfaction
• Accepting attitudes about sexual relations outside the relationship
• Attachment insecurity, both avoidant and anxious
• Differences in individual levels of sexual inhibition and excitement
• Being a man versus a woman (though this may be changing)

Those findings are mostly from the literature on marriage, with some findings from unmarried relationships. (For a deeper review of factors associated with greater odds of cheating in unmarried relationships, click here and here for reports from an earlier study drawing from the same project sample as the new study.)

The new study does not focus on predictors of infidelity, but rather on the likelihood that it will be repeated, and it uses particularly strong methods for doing so.

Following People Through Two Relationships

Most studies of infidelity are retrospective and cross-sectional, focusing on single points while asking about present and past relationships.[vii] To my knowledge, this new study is unique, because people were followed in real time (or close to it) from one relationship into the next, completing comprehensive surveys about their relationships at each time point during the longitudinal method. Contrast that with a method in which, for example, you asked a sample of middle-aged people if they had ever had sex outside of one or more relationships in their past. That would be a different study which, while interesting, would be subject to retrospective bias. People are believed to remember things better—and to report them more accurately—when asked closer in time to when the events occurred. That’s what Knopp and colleagues did.

For the new study, the overall national sample from the project started with 1,294 individuals. However, the analyses for this study had to be based on those who were surveyed across two relationships over the course of the five years that the sample was followed. This means that only those who had broken up from one relationship and then entered another during that period would be analyzed. That left 484 individuals. (For the questions addressed here, this sample is large and more than sufficient.)

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The average duration of the first relationship was 38.8 months, while the average duration of the second was 29.6 months. Thus, the relationships studied were mostly serious and of substantial duration. No one was married at the start of the project, but some would have married that first partner or the second during the time frame of the study. For the most part, however, it is best to think about these findings in the context of the stage of life in which people are often seriously involved, but not yet married—a stage of life that has grown substantially in the past few decades.

At each time point (which tended to be every four-to-six months), participants were asked, “Have you had sexual relations with someone other than your partner since you began seriously dating?” Participants were also asked if they had either known or suspected their present partner of having sex with someone else. Obviously, there are biases when people self-report such behavior, but that’s a problem for the entire literature. Further, the specific questions used in this study may exclude emotional affairs, as well as some online affairs in which there is some sexual aspect, but the respondents tell themselves they are not actually having sex. (Also, in such a sample there would be some small percentage of people who would have been in some sort of consensual non-monogamous arrangement, in which having sex with someone outside the relationship would not be the same as cheating, because there was some agreement about this. Knopp and colleagues note that there is no way to isolate such relationships within this data set, but there are strong reasons to believe that such open relationships are a very small percentage of the overall sample.)

Knopp and colleagues controlled for some of the variables known to be associated with a greater and lower risk of being unfaithful, net of other factors like relationship quality and commitment to one’s partner. That is, the study controlled for age, gender, socioeconomic status, and race.

Then and Again

Forty-four percent of this sample reported having had sex with someone other than their present partner in one or both of the relationships studied. Further, 30 percent reported that they knew that at least one of their partners in the two relationships had cheated on them. That seems to me like quite a bit of infidelity. Nevertheless, keep in mind that this is not a good estimate of the odds that someone will be unfaithful in an unmarried relationship. To be in this sample, a person would have had to have broken up in at least one serious relationship and entered another. Thus, this result does not mean that 44 percent of those under 40 in the U.S. have been unfaithful to a partner, and it certainly does not mean that such a high percentage of people who get married in a similar age range have been or will be unfaithful. Getting that percentage measured correctly would require a different type of sample and method. Closely related to that question, Galena Rhoades and I found in a previous study that 16 percent of those followed into marriage in the study’s parent project reported that they had cheated on their eventual spouse sometime before their marriage.[viii]

In this new study, 45 percent of individuals who reported cheating on their partner in the first relationship reported also doing so in the second. Among those who had not cheated in the first, far fewer (18 percent) cheated in the second. While the odds of cheating on a partner were far greater if one had done so in the past, a person cheating in one relationship was not destined to do so in the next. In fact, slightly more people who had cheated in the first relationship studied did not report cheating in the second.

The study also found that those who were certain that their partner in the first relationship had cheated were twice as likely as those not reporting this to experience a cheating partner again in the second relationship. History was not destiny, but it did speak to greater odds of a repeat experience.

Implications

It would be incorrect to assume that one is destined to endlessly repeat painful relationship patterns. And yet, some people are at much greater risk than others for negative outcomes in romantic relationships and in marriage, and they are at greater risk for repeat experiences. Some people are simply more likely than others to cheat on their partners, and some are more likely to choose partners who cheat on them, and to do so in more than one relationship. This touches on the complex subject of selection into risk, which Rhoades and I have written about more than a few times—for example, here and here.

The study described here was not designed to address complicated questions, such as how the risk of infidelity might be lowered in relationships and marriage, or how it could be prevented from happening again. Future research could examine what predicts whether someone who cheated on one partner is likely to do so again; however, most of the same predictors of ever cheating will predict repeatedly cheating quite well. Among all of the factors associated with cheating, some are surely more amenable to change than others. Variables that are biological (e.g., differences in proneness to sexual excitement) or cultural (and thus impacting individual values) are in the mix, but so are other factors, like commitment, which I believe people do have some control over.

Rhoades and I have described how relationship histories may play an important and causal role in eventual relationship quality in marriage (or not in marriage, for that matter). Specifically, while having more experience in various aspects of life is usually a good thing, having more experience in relationships may not be so good when those experiences include serious involvements that alter one’s odds of succeeding in finding and keeping lasting love. Nevertheless, behaviors of the past do not have to be the definition of one’s future.

I first released this piece at the blog at the Institute for Family Studies on 9-26-2017.