Why hasn't anything worked out?

I have significantly more guy friends than girl friends. My relationships with each of these friends is very platonic. A lot of the time, I'll really like a guy and over the course of getting to know each other we become best friends. The other day, I was told by one of these friends, "You're smart, and funny, and nice, why haven't you had a boyfriend?" And I was wondering why the pattern seems to be that all potential BFs become BFFs.