It's incredible how pepole here don't understand anything about "love" and attraction.
Attraction is not a choice, you can't choose to love someone, and you can't blame anyone for not loving you.
Every guy here have probably broke at least one girl's heart, you probably don't know it though (I broke the heart of at least four girls that I know, and it really was hard for me to disappoint them like that), does that make you stupid for "not realizing" how amazing she is? No, you're just not attracted to her, while she was to you, it's pretty much the same.
How the hell can you blame the girl for "not realizing how amazing he is"? Maybe she does, but just isn't attracted to him? Would you have been attracted to her if she was ugly? What if you're just a shallow person?