The good news is that he’s moving out of the apartment with her in four months. Until then, try not to bring up this subject. You’re not going to make it better. And try to stay away from her whenever possible. Being one big happy family as a threesome won’t work.
As for your boyfriend not trusting you, if that’s true and it’s not just this one situation where he doesn’t believe you, then you may have a more serious problem at hand. Understand that this relationship is still new for you and continue to get to know him and let him get to know you so you can figure out if he really is someone you want to continue investing your time in.
I hope that helps. Let me know how things go — and please follow me @AskAprilcom on Twitter.
