Myra, sex isn't just something enjoyable. It's not a game of scrabble. There's an inherent emotional aspect to it. Also, while humans may not be a strictly "[font=Tahoma, Verdana, Arial, sans-serif]monogamous[/font][font=Tahoma, Verdana, Arial, sans-serif] species[/font]", they do exhibit pair bonding, and there's some evidence to suggest the ability to pair bond is weakened the more sexual partners somebody has. Social norms also exist for a reason and while they can change for the better, mindlessly rejecting everything "traditional" doesn't necessarily improve people's quality of life or happiness.