I've (27F) been with my partner (30 trans masc) for 1.5 years and we've been open the whole time. We met through my ex (open relationship for 5 years that ended last spring—breakup was mutual but pushed more from my side). My ex and my current partner were dating for 1-2 months, my ex introduced us and we started dating, and they ended up transitioning to being FWB (and still are).

My relationship with my partner is really lovely. He's super affectionate and loving, but being trans, he experiences gender dysphoria and it often "gets in the way" of us being intimate. When we have sex it's great, but it's not very frequent. He only experiences dysphoria when he sleeps with women/AFAB people, and is able to not feel dysphoric with men.... So he sleeps with my ex and while I don't know details of their sex life, I know sex isn't an issue for them, and that they have it regularly. My ex and I are on fairly good terms but I have qualms with the way he treats people, he was quite the ass to me throughout our relationship, and he has also treated my partner badly so I'm generally not a big fan of their relationship, but that's none of my business and I don't poke my head where it doesn't belong.

I don't experience jealousy when my partner sleeps with other people... At all. Except. For. My. Ex. I've tried SO damn hard to figure out how to be okay with it, but I... I just can't. I know it isn't rational, but every time my partner turns me down sexually I can't help but think about how he has no issue fucking my ex and it makes me feel rejected and like a second choice.

On another note, my partner and I have a set, weekly date night. A couple months ago, he asked if we could shift it to another day. The day of our usual date, I asked what he was up to but he dodged the question. When we met up, I jokingly asked what he was so busy with. He said he saw my ex and wanted to talk about it in person rather than via text as he figured I'd have some feelings about it. I was hurt because of the principle of moving our set date night to see my ex, but I was especially hurt he wasn't upfront about the reason and purposely ignored my question—I felt like I was lied to. We had a good chat and he said he understood where I was coming from and agreed that in the future, if he wanted to shift our plans to be able to see my ex, that he'd let me know so I wasn't in the dark. We agreed that neither of us want him seeing my ex to be some weird secretive thing, and talked about balancing that with the fact that I don't want details of their relationship. I left the conversation feeling really assured.

Cue last weekend. He asked to cancel our date night (we spent a lot of time together during the holidays so I figured he wanted down time) but we ended up running an errand together the day after our usual date night. I mentioned that a plant of mine fell last night, and he said that was so weird because he slept at my ex's and one of his plants fell that night too. Part of me was utterly crushed because it felt like the whole conversation we had mere weeks ago about the exact same thing meant... Nothing. I could tell as soon as he said it that he hadn't intended to tell me he slept over but slipped up. I didn't say anything because I wanted to take some time to think about it.

I'm at odds here for multiple reasons. I don't want to (and won't) police my partner's life, who he sees, what he does. That feels gross. I also do not want to feel like a second choice after my damn ex boyfriend. I don't want to ask my partner to stop seeing my ex because, first, that's not my place, and second, if I do and he says yes he'll resent me for it, and if he says no then I guess the only option would be breaking up... Which fucking sucks because I really love the relationship we have, but I don't think I have another choice here. I don't know what to do but this situation with my ex is fucking gnawing at me.

What do you all think? Is there something I'm not thinking of? How would you go about this? And please be kind in your responses. Thanks in advance!