maybe you should introduce the girl to him, get them talking, that should get him back on your good side
ooorrr... you could always hook up with the chick, and "just happen" to be having sex on the floor of the front room when he gets home one day
I'm going to ask her out just to see how my roommate reacts.
Do it and post back.
Thinking of it, I may be doing the same thing on monday. One the people in my shop class decied to move a face frame i was making. He has been talking to this one girl for a good while. I got a dance comming up, and I need a date:p
Rember kiddies, find out if your GF's parents like you and will let their daughter date you;)