Roommate and jealousy

I'm guessing when she is not there you are all good...and when she's there you feel like crap...well it's probably because you feel as though she is taking your place which means you have feelings for him and in some way should lay that out on the table with him.

Probably because you are into him.

Are you currently in a relationship?
because if you aren't, maybe you get jealous because you want what your roommate and his girl has.

Or that he doesn't spend as much time as you want with him, because of this girl.

Thats what I think. hope it helps