Many people in relationships get jealous of good-looking waiters or strangers in clubs, but you might want to keep an eye a little closer to home.
A survey has revealed that more than half of people who cheat do it with someone they know.
The study, which was carried out for Superdrug by Forktip, found that 22.4% did the dirty with a work colleague, while a shocking 23.8% got off with their partner's best friend.
Some 3.9% of the 5,000 participants said they had played away with a member of their other half's family.
Now that's cold...