I've seen white girls with asian guys. Maybe this is a problem unique to where you live, but I think the reason that you see asian girls dating white boys is because the white boys are asking them out.
Also, I think some white boys buy into stereotypes about asian girls, particularly the one about them being more docile than white girls, and figure asian girls will put up with more crap. My brother (who is married to a Japanese girl) says this isn't true, though, and that asian girls are more passive-aggressive than white girls.
By the way, I have a very favorable opinion of asian guys and I am a white female. My first crush was on a boy named David Kim when I was in 5th grade.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?