Is it ok for a thin/beautiful woman to date a bigger/overweight guy?

Ughhh I am dating the greatest, sweetest, boyfriend that I could ever ask for! He is ALWAYS there when I need him and he's not like those guys who's egos are bigger than they are. Generally, he just knows how to treat me to a "T". But the one thing or drawback I guess most people see in him is he's fat. Everybody says that I'm a gordeous girl who should be with somebody like me. God do I HATE THAT! I dont think I'm so gordeous that I can't be with who I feel right with. Plus, its not even that my bf is ugly, because he is one handsome guy! He has a smile to die for, but....he's just fat! I dont know in my school we get looked at and talked about and I just hate it! On top of that all the guys in my grade are such egotistical jerks and I would never want to be with them. So really, can somebody tell me why it seems to be such a problem in our society if your average pretty girl wants to date a bigger man? And by the way my bf is fat but he's not obese.