Bagheera has done an excellent job of expressing the reasoning behind cheating, though not justifying it. I also live in a relatively sexless marriage and I have not cheated. But you sound exactly like my wife did when she found out the husband of one of her acquaintances had cheated after five years of no sex and separate bedrooms. My wife's reaction was the same as yours "how could he!" Mine was quite different (and probably most mens') "what right does she have to complain?" The way a man sees it, you have broken a contract, deal, agreement or whatever by no sex. In a man's mind and by even Biblical standards, that is what separates a friendship from a marriage. If the wife has elected to have a friendship instead of a marriage, then deep down, a man feels single again. Look at it this way. If your husband decided he would no longer provide for the family, should he get upset if you do? For a man, sex in a marriage is just as implicitly expected as provision. By the way, you need to be REALLY carefully about calling him perverted. Having sex is not perversion, having sex with animals or children is. When you call your husband sick and perverted, that is what he hears! By the way, I am not defending your husband and I hope I did not come accross too harshly, but you asked for a man's perspective. I am assuming since you are having sex, that there is some hope for your marriage and I hope you make it through!