A new research has suggested that relationships in which the woman is more attractive than the man are more likely to fail.
Scientists from Stirling, Chester and Liverpool universities found that beautiful women seem to realise they can pick and choose their mates, whereas an attractive man with a more ordinary woman seemed to be more content and less likely to stray, reports the Telegraph.
Researchers took photographs of men and women in over 100 couples, some of whom had been together for a few months, others for many years, and they were then rated on looks.
Rob Burriss, one of the researchers, said: "This would indicate it is the woman who is in control of whether the relationship continues."
He added that beautiful women may realise they can afford to pick and choose.
Conversely, the less attractive women "may have to make do with what they have, hence the longer relationships", he said.
The work was published in the journal Personality and Social Psychology Bulletin.