Longest relationships tend to stem from FIFTH LOVER!

How you act between the sheets also matters. Some 26 per cent of men believe that a successful relationship needs to involve good sex in order to succeed where as only 13 per cent of women believe this to be true.

MSN's relationship expert and psychologist Corinne Sweet says that the reason we wait till partner number five to settle is because we are most sure of ourselves then.

'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.