It is shallow but at the same time it isn't really, if one partner wants a sexual relationship and the other doesn't they aren't really fulfilling the others needs... not saying that gives the right to cheat but at the same time it gives more of a reason too and in fact is the reason why ALOT of men cheat, because at the end of the day lets face it men need sexual satisfaction on a basic level, and if they can't find it with their partner then... frustration and bad things can happen xD
You're a real lad xD