Here's my two cents:
Women in general (not everyone, but many) are maternal and relationship/communication oriented. We like having boyfriends because we have someone to care about and to care about us.
That being said, the reason a lot of us Greek ladies start freaking out about fraternity boys not wanting committment is because college is often our best chance to meet guys. Think about it...you meet new people almost everyday when you're in college but, once you graduate, you become confined to your office, classroom, lab, etc.
I'm 21, I'm not in a relationship, and I think I'm very "dateable." I don't
need a guy to complete me, but that I still get lonely sometimes and wish that I had a guy (especially since many of my sisters are in serious relationships and are starting to get engaged/married). All the guys I meet are either 19 or over 23 and usually are in a relationship, which is sooooo frustrating!
So, in closing
, while their are no perfect guys
or girls (Greek or not), we (sorority girls) blame you (fraternity guys) because you are our frame of reference, the ones we hang out with and are often closest to.