My boyfriend's girlfriend is moving in, and I'm not
I've been dating my boyfriend for five months, and he's been dating his other local girlfriend for about four months. She and I get along well, and recently we've been trying to spend more time together, the three of us. He's been having financial issues, is going through a divorce and custody battle, and has come to the point where he needs to have a roommate to keep himself afloat.
He offered the chance to move in to me early in our relationship, and I declined, because I didn't want to become the roommate of someone I'm involved with; if I move in, I want it to be more permanent, and because he wants to have me around. I didn't want to move in with him for strictly practical purposes, and honestly, it's just too soon in my opinion. He agreed that that was for the best. But now, his other girlfriend has agreed to move in to help with bills. He's told me that she'll have a seperate space (a room in the basement), but that she'll be able to share his bed.
I'm really not comfortable with her moving in, and I've told him that this might be a deal breaker for me at this point in our relationship. Scheduling is somewhat tight with him as it is (primarily because he is a part-time single dad), but I've been handling it by telling myself that she and I are getting roughly equal amounts of time with him. If she moves in, that will no longer be the case. I feel like I'm going to be losing what time I get to spend with him. Although I know that it's not intentional, and that I had plenty of opportunities, I kind of feel like I'm being punished for not accepting his offer to move in.
Both of them are willing to negotiate so that I feel more comfortable with the situation, and I'm certainly willing to compromise, but I don't know how to feel better about the situation.
Would it be wrong to ask that the situation be temporary? I won't feel comfortable spending time at his house if she's living there, which is where we spend alot of our time currently. I've told him that he'll need to spend more nights at my place, which he told me that he'd considered to be a solution as well, but I'm not sure that this will be enough. Are there other things I should ask to happen/not happen that might make me feel better about this arrangement?
This is the first poly relationship I've ever been in, and I just don't know what to do with these feelings. I am far more upset about this than I want to let on to him.