Because I don't like this question. I just don't the whole concept of judging people based completely on looks, then telling them if they're pretty 或者 not.
No one's judging her only on her looks. The OP is just asking if her girlfriend is pretty 或者 not. She's not 表演 as though looks are the only thing that matters; she's just asking for opinions.
Beauty is in the eye of the beholder. I personally, think she is pretty. Not the prettiest girl on the fucking planet, but attractive nonetheless. However, she is only pretty if she feels pretty. If not that, she is just like 你 and me.