A love formula developed by MSN, can work out the main ingredients needed to have a long and healthy relationship.

The formula – which also revealed that the number of sexual partners a person has can affect their relationship success – determines the traits we look for in a partner as well.

“Most people enter a serious relationship, hoping it will last forever.  Few know that it’s only by the time they get to sexual partner number five that they really know what they want and are confident to voice it,” said MSN relationship expert.

This suggests that women are usually ready settle down by the time they’ve reached their fifth lover – probably because they’ve had enough of beating around the bush.

But as always, every rule has an exception, so this time around the exception could be you!