Why are guys such jerks?

This is a specific/general question. Homecoming is coming up and I know that now boy is going to ask me. None of the boys at my school think of me as someone to go to a dance or go out with. And only a few (and I mean few) people at my school like me. Just about all the guys are mean to me. Just about everyday I come home crying (and I am seeing someone for it). My mom says I’m pretty all the time, but compared to the other girls at my school, apparently I’m not. I know looks aren’t everything, but in this case they sure do help.