Why do Girls at College like me simply because they think i'm Good Looking?

Sounds like me, but the other way around. I was born like 2 months before I was supposed to be, do I look good? No, but my girlfriend don't really care about my looks and just looks beyond that. I also find that stupid also how most girls only like the good looking guy that will probably treat her bad instead of the not so good looking guy that will treat her really good.