I've seen some instances where the women were the ones who temps men to cheat (consciously or unconsciously). What would a guy do if a temptation appeared with that instinct of theirs and the girl gave the green light? -- Grab the opportunity, thus leading to them cheating. It's a guy's instinct to stare if the woman is attractive. It's not like they are cheating if they do that unless there's a physical contact between them. I am not defending the guys that cheat, I am just giving them the benefit of the doubt. But still, you are correct, some guys are really morons.
You've said it yourself "It's a guy's instinct". Your first paragraph and second contradict eachother. How can a group who's more likely to cheat not cheat more? But I get what you were trying to say.
Oh lordy, "a guy's instinct". If there's one phrase that perfectly sums up the EvoPsych bullshit justifications for what is societally acceptable...
Honestly, guys don't cheat because of biology or w/e. Guys cheat because society has traditionally condoned, if not encouraged such behaviour much more by men than women. The old "guys are playas, girls are sluts" thing, with a side order of "a man has needs!" while denying that women have any needs at all. But these days you gotta lay a thin layer of semi-scientific justification over it, make it sound legit.