Why is it so hard to lose your virginity?

I'm a young girl and I consider myself quite pretty.

I've been interested in a lot of guys, but nothing ever happens. They always screw up or it just doesn't work out.

I have friends younger than me who've been doing it since they were very little, and they're much uglier than me.

Am I doing something wrong? I don't want to be the virgin friend in the group...