The natural purpose of sexual intercourse is reproduction. Homosexual intercourse cannot result in reproduction, therefore it does not fulfil its natural pupose. Really? Then why only humans and dolphins enjoy it? And in general, if sex's only purpose is reproduction, why do we enjoy it? If food's only natural purpose is nourishment, why do we enjoy it? It's a side effect, it is irrelevant to the natural function of it. I've already gone over my problem with multiple marriages, I don't see what you're trying to prove. This is a primal instinct, one that as humans, and not merely animals, we can and have forgone throughout history. Not at all, today more than ever males are out seeking to mate with as many females as possible. It exists today on a very large scale. Because society today tells us its ok to [bleep] whoever we want with no thought for the consequences. What? Cheating is nothing new. The Bible itself poses rules against affairs, etc ("You shall not commit adultery" / "You shall not covet"). But these have become morewidespread as people lose respect for marriage.