The Chief primary reason why pretty girls get cheated on is the fact that pretty girls are lazy. Yeah I said it most pretty girls are lazy. They think that just cause they fine it gives them an exemption from any form of physical or even mental labor, thinking that with a bat of the eyelid they can get people to do it for them.
How do I know this? From personal experience, dude!! And some of you fellas know what am talking about. Just cause she thinks she is all that, a girlfriend would come to her boyfriend's place to spend the weekend and the lazy girl would let the poor dude cook meals, wash the dishes after the meal, sweep the house while she sits down doing nothing but watching TV. Some girls would defend this act by saying "she ain't his housegirl", well you may have a point but that's just plain old laziness talking. Some of these girls even take this laziness to bed and just lay down and let the poor guy labour away trying to please her and himself at the same damn time.
On the other hand the so called "ugly girls" because of the hand nature has dealt them tend to make the best of every situation. When they come to visit a guy they immediately make their presence felt, by making sure that they clean up their surrounding, cook the fella a decent meal, wash his clothes (now aint that a wife material). And to top it off they tend to work it in bed, try new things and please the dude. Now why won't that dude keep going back to her.
Beyond the domestic front, just think about it, in the university which girls do better in school. Is it the pretty girls or the not so pretty ones?
In the end it all boils down to the simple fact that most pretty girls are lazy that's why ugly girls ( the word "ugly" being debatable) are getting married every weekend while the pretty girls rock asoebi.