Originally Posted by wehateporn

Fundamentally this comes down to reproduction, if a girl is sleeping around you could end up fathering some other guy's kid, so from a man's perspective this is bad, his genes can become extinct from the pool. From a woman's perspective she wants the man with the best genes, if she's capable of getting the knickers off hundreds of other girls he must be something special, so any girl wants to reproduce with his genes.