"Once A Cheater, Always A Cheater" – Is There Any Truth To The Phrase?

One study found that people who cheated in past relationships were three times more likely to cheat in their next relationships.


Maddy Chapman


Maddy Chapman

Copy Editor and Staff Writer

Maddy is a Copy Editor and Staff Writer at IFLScience, with a degree in biochemistry from the University of York.

Copy Editor and Staff Writer

Cheating in relationships

Maybe it's a red flag for a reason, or maybe not.

Image credit: Estrada Anton/

“Once a cheater, always a cheater” – it’s an adage you’ve no doubt heard before, perhaps you’ve even said it yourself, red flag waving, but is there actually anything in the phrase?

While many people believe that a track record of infidelity in relationships is a surefire sign of future adultery, that doesn’t necessarily mean it’s true – but it also doesn’t mean that former cheaters are off the hook, either.


One study published back in 2017 shed some light on the matter, attempting to pinpoint the likelihood of repeat misdemeanors. Researchers looked at 484 mixed-gender couples, finding that 44 percent of participants reported engaging in infidelity at some point during the relationship. 

The analysis also revealed that those who had cheated in the past were three times more likely to cheat again compared to those who had never dabbled in adultery.

“The past matters for relationships,” study author Kayla Knopp said in a statement. “What we do at every step along the way in our romantic histories ends up influencing what comes next.”

That may be true of infidelity, in some cases, but it’s not a hard-and-fast rule.


“Not every person who cheats once will cheat again,” psychologist Kristin Davin and neurologist Heidi Moawad write for Choosing Therapy. “However, serial cheaters are people who seek out sexual partners on a continual, chronic pattern of infidelity.”

Although no such official term exists in psychology, there are certain personality traits that may make some people more likely to be unfaithful, therapist Ainhoa Plata told El País. These include those with narcissistic personality disorder. 

Narcissistic people use others to feel loved and admired. They like challenges and continually prove to themselves that they are above others. For this reason, they love to live the passion of falling in love… they feel more admired and valued in that space than in a long-term relationship,” Plata continued.

“The narcissist is not satisfied with a stable and lasting relationship, because over time, their partner gains independence and stops idolizing them. Infidelities [subsequently] satisfy the needs of the narcissist.”


People with avoidant attachment styles or low self-esteem may also be prone to serial cheating – perhaps they may rebel against commitment or seek validation in others, Inés Bárcenas told El País.

“That being said, not all people who are unfaithful have personality disorders or mental problems,” Bárcenas added. “Sometimes infidelities do have to do specifically with a partner.”

Of course, there are also a whole host of other reasons why someone might cheat time and time again, but the good news is, these can be remedied, and serial cheaters can be reformed.

“There are no quick treatments. You have to work on identity, self-esteem… it’s a very long path that involves exploring and reconfiguring the link between oneself and others. But yes, it is possible to get better and be better for others,” Bárcenas concluded.


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  • psychology,

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  • infidelity