Infidelity Statistics

How Many Affairs Result in Marriage?

DivorceThis is a question that we encounter a lot from faithful spouses who are trying to understand what they’re facing when their cheater is actively in an affair.

We’ve tried to put a number on it for people, to give the issue some context. Obviously, the numbers aren’t absolute and will be relatively inaccurate because we’re working with prevalence data derived from research, not absolute census data.

One of the biggest problems in trying to get a handle on actual figures is that we won’t ever be able to capture the real incidence of marital infidelity (let alone relationship infidelity) and even the modern statistics we do have are hindered by misinformation and non-disclosure. It’s worth stressing that all the research figures are only as accurate as the originating data.

The Statistics

statisticsHowever, working from the 2010 census figures and other available research figures, we’ve tried to illustrate how unlikely it is that an affair relationship will survive long-term, even if it results in the affair partners marrying.

Assuming that 50% of US adults are married (though that is a declining trend), and that approximately 40% of marriages end in divorce (27% of them as a result of infidelity), and that approximately 5% of affair partners marry (we rounded it upwards from the 3% cited specifically for men), we made some simple calculations.

Using these figures, we can calculate that the cheater and the affair partner have an approximate 0.13% chance to be in a lasting marriage together.

Just as desperately as faithful spouses wish that their cheater’s affair is not part of that 0.13%, many affair partners and cheaters wish equally that they were.

Faithful spouses can’t count on this data as a reason to stagnate in hope that their cheater won’t be part of that 0.13%. Similarly, love-struck affair partners and cheaters can’t count on their relationship being in that small 0.13%.

Very few will be part of that statistical demographic, and even fewer will be statistical outliers that are the ‘exception to the rule’.


We’re not suggesting that our calculations are statistically valid or tested, 100% accurate, or take account all relevant factors - we’ve worked strictly with the information we’ve cited. However, they do give a ballpark context to the fears that many faithful spouses face.

While the numbers are derived specifically from US data and therefore apply specifically to US adults, they may be a similarly useful guide for people in other countries with similar cultures and social trends.

Clearly, there could be other influencing factors that would affect the likelihood of an enduring affair-to-marriage relationship, but the figures show a definite leaning towards a significantly low statistical probability of that happening.

It should also be noted that this doesn’t provide any insight into the quality of the lasting marriages, and doesn’t account for data that might be gathered in any longitudinal studies.

More Infidelity Statistics

We have included other statistics on the site from the Kinsey Institute (below), pop-culture infographics (here), and other tabulated data (here).

The Kinsey Institute

The Kinsey Institute has been investigating critical issues in sex, gender and reproduction since 1947 and offers the following information about infidelity and affairs:

  • Infidelity has been found to be the single most cited cause of divorce in over 150 cultures. (Betzig, 1989)
  • In western countries, between 25 and 50% of divorcees cite a spouse’s infidelity as the primary cause of the divorce. (Kelly, 1987; Amato, 1997)
  • Approximately 20-25% of men and 10-15% of women engage in extramarital sex at least once during their marriage. (Laumann, 1994; Wiederman, 1997)
  • Pregnancy appears to be a time of increased risk of extramarital sex. (Allen, 2005; White, 1982)
  • Women are less approving than men of sexual justifications for extramarital affairs, preferring emotional reasons such as “falling in love”. (Glass, 1992).
  • Approximately 50% of divorced men and women reported that their former spouse had engaged in extra-marital sex. For divorced couples, previous participation in extramarital sex showed no effect on post-marital adjustment. (Spanier, 1982).
  • 11% of adults who have ever been married or cohabited have been unfaithful to their partner (Treas & Giesen, 2000).
  • Infidelity is influenced by many social and demographic factors. All of the following were associated with an increased risk of infidelity: having been part of a couple for a long time; having had a high number of prior sex partners; being male or black; living in a central city; and thinking about sex several times a day (Treas & Giesen, 2000).
  • Respondents who reported that their relationships were “pretty happy” and “not too happy” were two and four times more likely, respectively, to have reported extramarital sex than respondents who reported that they were “very happy” with their relationships (Atkins et al., 2001).
  • More than 80% of women and 65 to 85% of men report that they had no partners other than their spouse while they were married (Laumann, Gagnon, Michael, Michaels, 1994).
  • 94% of married men and women had only one sex partner (their spouse) in the past 12 months, 4% had 2-4 partners, and 1% had over 5 partners (Laumann, Gagnon, Michael, Michaels, 1994).

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