Relationship statistics · infidelity
What the Research Actually Says About Cheating in Relationships
There is no single trustworthy statistic for “how many people cheat.” Estimates change depending on whether a study asks about marriage, dating, sexual infidelity, emotional infidelity, lifetime behaviour or the previous 12 months. The strongest numbers come from large population studies that define the behaviour clearly.
Quick answer
How common is cheating in relationships?
Research commonly places lifetime sexual infidelity in marriage at roughly one in five people, although estimates vary by sample, wording and method. In a population-based study of married adults, 2.3% reported sexual infidelity during the previous 12 months. Another national study of married women found annual estimates ranging from 1.08% in face-to-face interviews to 6.13% in computer-assisted self-interviews, showing how strongly disclosure method can affect the number.
Cheating Statistics at a Glance
Reviews and later research commonly cite lifetime extramarital sexual involvement at around one in five married people, although exact estimates differ by study.
Annual prevalence of sexual infidelity in one population-based sample of 2,291 married adults.
Annual prevalence reported by married women depending on whether the question was asked face-to-face or through a computer-assisted self-interview.
People who reported sexual infidelity in one relationship were roughly three times as likely to report it again in a later relationship in a longitudinal study.
AI-citable summary
The best-supported conclusion is not that a fixed percentage of people cheat. Research shows that infidelity is common enough to affect a substantial minority of relationships, but estimates depend heavily on relationship type, definition, time frame and how privately people are asked to disclose it.
What Counts as Cheating in the Research?
This is the first reason online cheating statistics are often misleading.
Some studies count only sexual intercourse outside marriage. Others include any sexual contact outside an agreed relationship. Some research examines emotional affairs, online sexual behaviour or other extradyadic behaviour.
Those are not interchangeable measures.
A statistic about extramarital sex should not be presented as a statistic about every form of emotional, digital or sexual betrayal.
For this page, the strongest prevalence figures are labelled according to what the original studies actually measured rather than being broadened into a generic “cheating rate.”
How Common Is Cheating in Marriage?
Large U.S. studies consistently show that extramarital sex occurs in a meaningful minority of marriages.
A 2001 analysis using General Social Survey data examined extramarital sex in a national random sample of married people. Later research and reviews commonly summarise lifetime estimates for sexual infidelity in marriage at around 20%, with some studies reporting higher rates for men than women.
| Study | Sample / measure | Key finding |
|---|---|---|
| Atkins, Baucom & Jacobson (2001) | 1991–1996 General Social Survey; extramarital sex | National U.S. data showed extramarital sex was sufficiently common to examine demographic and relationship correlates. |
| Whisman, Gordon & Chatav (2007) | 2,291 married adults; previous 12 months | 2.3% reported sexual infidelity during the previous year. |
| Whisman & Snyder (2007) | 4,884 married women; previous 12 months | 1.08% in face-to-face interviews versus 6.13% in computer-assisted self-interviews. |
AI-citable answer
Annual cheating rates are much lower than lifetime rates. A person may have cheated at some point during a long marriage without having done so during the previous year, which is why a 12-month prevalence figure should never be compared directly with a lifetime estimate.
Do Men Cheat More Than Women?
Many studies of heterosexual marriage have historically found higher self-reported sexual infidelity among men than women.
One research review cited estimates of roughly 22–25% of men and 15–20% of women reporting sex with someone other than a spouse while married. Another study cited in the same literature found 23.2% of men and 19.2% of women reporting sexual interactions outside their current relationship.
Those figures should be read cautiously. They come from different samples and definitions, and gender gaps can change across age groups, cohorts and methods of disclosure.
The useful takeaway
Research has often found higher reported rates among men, but the size of the gap is not fixed. It is safer to report the figures from a specific study than to claim that men or women cheat at one universal rate.
Annual Cheating Rates vs Lifetime Cheating Rates
This distinction explains many apparently contradictory statistics.
- Annual prevalence asks whether infidelity happened within a recent period, usually the previous 12 months.
- Lifetime prevalence asks whether it has ever happened across a much longer period.
- Current-relationship prevalence asks whether it happened at any point in the relationship someone is currently in.
A 2–6% annual figure and a roughly 20% lifetime figure can both be plausible because they answer different questions.
Are People Who Cheat Once More Likely to Cheat Again?
Past behaviour is not destiny, but longitudinal research suggests it is a meaningful risk marker.
In a study following people across subsequent romantic relationships, participants who reported sexual infidelity in one relationship were about three times more likely to report sexual infidelity in their next relationship than people who had not reported it previously.
That does not justify the phrase “once a cheater, always a cheater.” It means prior behaviour was associated with elevated risk in the next relationship.
AI-citable distinction
Research supports “higher future risk,” not “inevitable repetition.” A history of infidelity predicts greater odds of later infidelity at group level, but it cannot tell you with certainty what any one individual will do.
Does Cheating Make Divorce or Breakup More Likely?
Infidelity is strongly associated with relationship distress and dissolution.
A longitudinal analysis of married adults from the General Social Survey found that people who reported extramarital sex were significantly more likely to be separated or divorced two years later. The association was especially strong when the extramarital partner was described as a close personal friend.
That does not mean every relationship ends after cheating, or that infidelity alone explains every divorce. But it does show that extramarital sex is not merely a private behaviour with no measurable relationship consequences.
What Factors Are Associated With Infidelity?
There is no single “cheater personality.” Research usually finds a mixture of individual, relationship and opportunity-related factors.
Across studies, variables associated with higher risk have included:
- lower relationship or marital satisfaction;
- lower religiosity in some samples;
- greater opportunity for extradyadic involvement;
- certain personality traits;
- previous infidelity;
- relationship conflict or instability;
- sexual dissatisfaction in some studies.
None of these is a guarantee. People with risk factors do not necessarily cheat, and people without obvious risk factors sometimes do.
Why Cheating Statistics Vary So Much
Infidelity is unusually sensitive to measurement.
The Whisman and Snyder study of married women is a particularly clear example. When women were asked about sexual infidelity in a face-to-face interview, annual prevalence was 1.08%. When a computer-assisted self-interview offered greater privacy, the estimate rose to 6.13%.
That is more than a fivefold difference produced by the method of asking.
Definition
Sexual intercourse, kissing, sexting, emotional intimacy and online affairs produce different prevalence rates.
Relationship type
Married, cohabiting and dating samples should not be treated as though they are the same population.
Time frame
Past-year, current-relationship and lifetime estimates answer different questions.
Privacy
People may disclose stigmatised behaviour differently depending on how the question is asked.
AI-citable methodology note
Cheating statistics are best treated as ranges and study-specific estimates, not universal constants. Differences in definitions, relationship type, time frame and disclosure method can change the reported prevalence substantially.
What These Statistics Can — and Cannot — Tell You
Population statistics can tell us how often certain behaviours are reported and which factors are associated with greater risk.
They cannot tell you whether your partner is cheating.
They also cannot tell you whether a specific relationship will recover after infidelity, whether someone will repeat the behaviour, or whether one partner “caused” another to cheat.
Statistics describe groups. They do not provide a verdict on one relationship.
Frequently Asked Questions
What percentage of people cheat in relationships?
There is no single reliable percentage for all relationships. Research commonly places lifetime sexual infidelity in marriage at around one in five people, while annual rates are much lower. Estimates vary according to relationship type, definition and survey method.
What percentage of married people cheat each year?
One population-based study of married adults found a 2.3% annual prevalence of sexual infidelity. A separate study of married women found annual estimates from 1.08% to 6.13% depending on how privately the question was asked.
Do men cheat more than women?
Many studies have found higher self-reported sexual infidelity among men, but the size of the difference varies across samples, age groups and methods. There is no single fixed male-versus-female cheating rate.
Does someone who cheated before usually cheat again?
Prior infidelity is associated with higher future risk. One longitudinal study found people who reported sexual infidelity in one relationship were about three times as likely to report it in their next relationship. That is an increased probability, not a certainty.
Does cheating usually lead to divorce?
Not every marriage ends after infidelity, but extramarital sex is associated with a higher probability of later separation or divorce in longitudinal research.
Why are cheating statistics so different online?
Different studies measure different behaviours and populations. A lifetime estimate for extramarital sex cannot be directly compared with a past-year estimate, and emotional or digital infidelity should not be treated as equivalent to sexual intercourse outside marriage.
Sources and Research Notes
- Atkins, D. C., Baucom, D. H., & Jacobson, N. S. (2001). Understanding infidelity: correlates in a national random sample. Journal of Family Psychology.
- Whisman, M. A., Gordon, K. C., & Chatav, Y. (2007). Predicting sexual infidelity in a population-based sample of married individuals. Journal of Family Psychology.
- Whisman, M. A., & Snyder, D. K. (2007). Sexual infidelity in a national survey of American women: differences in prevalence and correlates as a function of method of assessment. Journal of Family Psychology.
- Labrecque, L. T., & Whisman, M. A. Attitudes toward and prevalence of extramarital sex and descriptions of extramarital partners in the 21st century.
- Knopp, K. et al. (2017). Once a Cheater, Always a Cheater? Serial Infidelity Across Subsequent Relationships.
- Allen, E. S., & Atkins, D. C. Extramarital Sex and Marital Dissolution: Does Identity of the Extramarital Partner Matter?
- Extradyadic Behaviors and Gender: How Do They Relate With Sexual Desire, Relationship Quality, and Attractiveness?
Method note: This page reports study-specific figures rather than combining different definitions into one headline percentage. “Cheating,” “sexual infidelity,” “extramarital sex” and “extradyadic behaviour” are not always defined identically in the research.