ALL of the man need the "cookie" by the cookie i mean sex, and your support. They will give you protection, they will provide you what you need, and they will tell everyone your his girl. If youre not doing something right or dont have standars he will look for a women that does!
First off as others said men arnt' the only ones who cheer women do too. It could be beacuse there not happy, it could be beacuse they need more sexual attention, it could be beacuse they were drunk. It doesn't make every one who's cheated a "dirtbag". It just might mean they made a mistake.