Cheaters will cheat...again, and again: Study shows infidelity is a pattern

Research from the University of Denver indicates that past relationship behaviours are a strong predictor of future actions, suggesting that infidelity often follows a repetitive cycle. The 2017 study, led by clinical psychologist Kayla Knopp, tracked 484 unmarried individuals in the US to analyse the "once a cheater, always a cheater" phenomenon. The team’s findings suggest that individuals do not always start with a clean slate when entering a new relationship. Instead, their romantic history tends to influence their future conduct. They noted that those who had been unfaithful in a previous relationship were three times more likely to cheat on their next partner compared to those who had remained faithful.

The ones who were betrayed, that is, the participants who were cheated on in a past relationship, were four times more likely to report being cheated on again by a subsequent partner. The study also noted that people who suspected their previous partners of cheating were four times more likely to have similar suspicions in later relationships.

Why the Past Matters

Knopp and her colleagues emphasise that these patterns reflect ingrained behaviours and partner selection. "The past matters for relationships," Knopp noted. "What we do at every step along the way in our romantic histories ends up influencing what comes next."

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Key Takeaway

The research suggests that for many, infidelity is not an isolated incident but a behavioural pattern. Whether it is a tendency for one person to engage in such behaviour or a subconscious pattern in how individuals select partners, the study highlights that previous romantic experiences serve as a critical blueprint for future relationship dynamics.

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Both men and women cheat, but with different motivations

Several studies have been carried out on infidelity, which show how things are changing. Historical data often showed a significant gender gap, but recent studies indicate that this divide is becoming smaller, particularly among younger groups under the age of 45. A 2016 study showed that while dissatisfaction is a major driver, it is not universal. It noted that 56 per cent of men and 34 per cent of women who cheated reported being "happy" or "very happy" in their primary marriage at the time. A 2023 study showed that approximately 50 per cent of individuals who engage in infidelity meet their outside partner through work.

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Men tend to experience higher distress when their partner cheats on them sexually, while women tend to be more upset by emotional infidelity. According to a study conducted in 2026, the reason why women cheat is often "unfulfilling relationships" and they rationalise their decision thoroughly. However, men may hold more permissive attitudes toward purely physical extramarital sex.