Experts believe mate-poaching can fill a relationship with doubt.

You might not have considered whether how you met your partner can predict the chance of the relationship’s success – but it does.

Research suggests that if you ‘mate poached’ your current partner – luring them away from their other half without actually cheating – they will be less committed, less satisfied and less invested in the new pairing.

The problem could be a huge issue, given an estimated 63% of men and 54% of women are in their current long-term relationships because their current partner “poached” them from a previous partner.

A study conducted by psychologists at the University of South Alabama found that “poachees” are also more likely to be alert to other potential partners and view them as “higher-quality” options.

Perhaps worst of all, they were also more likely to cheat than those who were not “poached”.

Over the course of the study, levels of these markers worsened. In contrast, those who weren’t poached were less likely to seek out different partners, the British Psychological Society said.

Researchers surveyed 138 heterosexual couples that had been in a relationship for 36 months. The average age of participants the was 20 and 71 per cent were women. A final survey of 219 heterosexual participants reflected similar results.

Psychologist Joshua Foster who led the research said: “Individuals who were successfully mate poached by their current partners tend[ed] to be socially passive, not particularly nice to others, careless and irresponsible, and narcissistic.”

“They also tend(ed) to desire and engage in sexual behaviour outside of the confines of committed relationships.”

As between 10 and 30 per cent of relationships – which researchers described as a significant proportion – were formed by mate-poaching, the psychologists said further work is needed to understand exactly how the phenomenon is damaging.

So what makes a successful pairing? A 77-year-study into relationships found that the happiest couples are not the ones that never argue, but rather those where each partner knows they are ultimately supported despite some minor bickering.

Robert Waldinger, clinical professor of psychiatry at Harvard Medical School, is the fourth director of the 77-year-long Study of Adult Development.

He told a TedTalk audience: “The clearest message that we get from this 75-year study is this: good relationships keep us happier and healthier: period.”