hot girls don't cheat when they're in a serious relationship that THEY perceive to be good.
most men will cheat in the same circumstance, especially if the risk of being caught is low.
for men, pussy is generally a commodity which has scarcity value. the opposite isn't true for women; meaning that there's no short supply of dicks for them. any reasonably good looking woman can have sex whenever they choose to have sex.
for women, a good relationship with a good man is a commodity.