When you first start dating, it makes sense that he’ll conceal the things he’s not particularly proud of: his messy flat, his mother’s daily phone calls, his hairy back. But by the time you’re a serious couple, you assume you know your bedmate’s every last idiosyncrasy. Right? Don’t be so sure.

According to new research published in the Journal of Sex and Marital Therapy, one in 10 men are harbouring a serious sexual secret. “There are two kinds of secrets guys keep,” says clinical psychologist Dr Les Parrott, author of Crazy Good Sex. “Things they wish their wives or girlfriends would understand but are scared they won’t, and things they’re just plain trying to get away with.”

With that in mind, we surveyed hundreds of men to find out what they’re hiding at different stages of the relationship and asked some experts to decode their behaviour. Unfortunately, what we discovered was that there’s a good chance your man is keeping at least one dirty secret.

Read on to find out what, if anything, you should do about it...