Originally Posted by MonoVCPHG
This statement is again very concerning. If you lose this much over a person and don't care then that indicates you are just about willing to do anything for some one to "love" you.
My original advise still stands. Find another room mate. Seriously.
She's 23 which likely means that her last bf was one that she had in her teens. A lot of us made bad decisions in our teens with the people we chose to date and lost friends because of it. Hopefully the OP has learned from that last relationship and it won't happen again.
On another note though, I have to agree with what the majority of people are telling you here. It's not a good time to have your bf move in with you. There is too much instability at the moment which is just going to be amplified if you're living under the same roof.
I get that you don't like his gf, you might not even understand what he gets out of the relationship. The thing is that his relationship with her really has nothing to do with you. If you can't just leave it alone and not let it effect you you're not going to be able to be fully satisfied in your relationship with him.