Most Helpful Guy
I've known guys to cheat on their girlfriends with less attractive girls. Its not about her being more attractive necessarily. For a lot of men being attractive to women is a huge part of their ego, nothing validates and proves you are attractive more than someone wanting to have sex with you. Essentially they did it to prove to themselves they still could, not because the girl was more attractive. Or they were just horny at the time and thought they'd get away with it. Or they suspected their girlfriend was being unfaithful or was about to be and they did to almost 'even things out' in their mind. Or they were just bored with sleeping with the same person all the time and wanted some variation. Or some other reason, there are a loads of possibilities, its not all about attractiveness, in fact I'd say its usually not.