Is it selfish of me to get upset when my partner uses some of our inside jokes with his other partners? Or when he tries to do things with me that he’s already done with them? I just want to have something special with him that’s between just us but it seems everything we have is shared with everyone else as well and it’s kind of upsetting to me because I feel there’s nothing special about me that would make him keep me around if he can do it with everyone else?

Have you told him you feel this way? It is perfectly fine to want something that’s just between you two - in fact, I am careful to cultivate inside jokes, pet names, traditions, etc. with individual partners that I don’t share outside that relationship.

(This has led to some entertaining poly-confusion: I only use the term “boo” with one of my partners. One day he asked me what I was up to on Friday, and I said, “hanging with my boo,” as a cutesy way to say, “I didn’t have plans, but now I’m setting that time aside for you!” But he didn’t know I had kept that term private between us, so he thought I meant “hanging with my other partner.” Friday came around and I thought we were on to hang out, but he had made other plans since he thought I was busy! Moral of the story is, if something is special with one partner…make sure everyone’s on the same page.)

My suggestion is to sit him and and say “hey, it’s not that I’m trying to put limits on your other relationships, but it would make me really happy to have something that was just special between us. Could we set up a tradition that you don’t share with anyone else?” If he says sure, then brainstorm together what that might be! You could also mention past examples of inside jokes he brought other people into, and gently ask if maybe he could keep things like that more intimate. 

If he gets defensive or accuses you of being too sensitive or controlling, take a big step back from this and think about whether this is working out for you. Requests like this are common and healthy and a major part of the open communication that makes poly relationships function. We are all human, and if what it takes to make us feel loved, respected, and special is a little compromise on a partner’s part, that’s a very reasonable request. You’re doing the right thing by being open and honest about it rather than passively resentful - so he should respond in kind.