Once a cheater, always a cheater? Couples therapists reveal if the theory holds true

Rachel said it to Ross when they were 'on a break' and you've probably warned a friend about getting back together with a previous partner who was unfaithful - but is the old adage true? 

Is it really 'Once a cheater, always a cheater'? 

About 40 percent of unmarried couples and 25 percent of married couples report infidelity in their relationships. 

And Dr Kayla Knopp, a clinical psychologist in San Diego, conducted a study that found people who cheat in one relationship are three times more likely to cheat in subsequent relationships. 

But she did offer a glimmer of hope, saying the absolute nature of 'always a cheater' may not apply to all those who have strayed, with plenty of people able to break the cycle. 

Dating and relationship coach known as 'Coach Ryan' on social media said people who cheat in one relationship are three times more likely to cheat in the next relationship 

Dr Knopp wrote in a 2017 study: 'Although a history of infidelity may be an important risk factor of which to be aware, it is not necessarily true that someone who is “once a cheater” is "always a cheater."'

The study involved 484 heterosexual people who were followed through two relationships.  

Researchers found most people who had reported that either they had been unfaithful or a partner had cheated in the first relationship, did not report having the same experience again in the second relationship.

Dr Knopp told Self earlier this month: 'Lots of people have a fear of being cheated on though, so believing in black-and-white rules [like "once a cheater, always a cheater"] can make them feel safer.'

Not everyone is doomed to repeat history though, Knopp said, and there are several signs a person has learned from past mistakes and will remain committed to future partners.

Our partners cheated on us using THESE bizarre apps: Women reveal how they caught their boyfriends using platforms like LinkedIn to betray them

Apps such as Snapchat, Instagram and Facebook are common places to look if you suspect your partner is cheating on you. However, more and more 'infidelity-lurkers' are turning to unlikely platforms to conduct their illicit affairs - such as LinkedIn.

Dr Knopp said if the person who cheated voluntary discloses their past infidelity - which can be either physical or emotional - it shows they want to be honest in their new relationship. 

She said: 'When someone voluntarily shares their mistakes, they’re much more likely to be a trustworthy partner in the future.'

Another sign is if the person knows why they strayed. 

Someone who skirts around the issue, doesn't take responsibility, blames their previous partner or claims they don't know what led them to cheat is showing 'red flags.'

Dr Knopp said: 'If [your partner] acts like it wasn’t within their control or claims they don’t know why they cheated, those are red flags.'

Being able to acknowledge and take responsibility for their actions are essential in correcting their behavior. 

Similarly, if they have taken action to learn from and own up to their mistakes, such as going to therapy or apologizing to the person they wronged, those are 'green flags.' 

K'Hara McKinney, a licensed marriage and family therapist, told Self it also matters how many times a person has cheated. 

Whether it was a one-time mistake or a pattern of multiple affairs can help determine if they are doomed to repeat the behavior. 

Dr Knopp added: 'Someone with a longer pattern of infidelity is definitely more likely to cheat again than someone who’s only done it once — unless they’ve done serious work on themselves.'

Dr Galena Rhoades, a psychologist and co-author on the 2017 study with Dr Knopp, said of their findings: 'The research points to how important it is that we talk with people about what their relationship experiences are and what they want to leave behind or take with them from those experiences into new relationships.

'Hopefully, by identifying risk factors, then that gives people a little more power and control in their own lives.

'That might be really important to discuss, so we can plan ahead to avoid unwanted outcomes in the future.'