No advice needed really, unless you see something glaring that I haven't yet. I have no one to talk to about this so I figure this is the best spot. Sorry if I get long-winded.

Partner, Josh, and I have been non-monogamous from the start of our relationship nearly 2 years ago. He identifies as polyamorous but I'd say I'm more into casual non-monogamy for myself; these minor discrepancies have never been in issue. He had a partner, Leah, at the beginning of our relationship and she ended up being really toxic, so that ended about 9 months ago. They were DADT for her comfortability.

When Josh was with her, it was difficult to deal with the "bleed over" of their relationship problems. Leah valued anonymity, privacy, and secrecy almost to a fault; it was the classic "I don't know how to deal with the feelings that come with polyamory, so I'm going to pretend we're monogamous as to not think about it" type of situation. I never saw it as my place to comment on their relationship and I had my own jealousies surrounding it, so I didn't. I always tried my best to keep my insecurities to myself and deal with them accordingly. In those early months, Josh would be upset and anxious for periods at a time due to fights with Leah, but never put any of his baggage onto me and I was grateful for that. But it was still tough knowing he was struggling and never getting to support him.

From the beginning of our relationship, Josh and I have been very open and honest about what we did outside of our relationship. Not out of obligation, mainly because we're very close and were best friends long before we started dating. After Leah and Josh ended things, we definitely made it clear to each other that we would be as transparent as possible within reason (not sharing specific details about our partners, but rather experiences we had with them).

Recently I reconnected with someone, Mason, from high school. I went to an incredibly small and religious school, so I was never really romantically interested in anyone back then. Sharing a drunken make-out with someone I never had on my radar was very exciting and new, and I wasn't expecting the physical chemistry we'd have. I began seeing Mason while hanging out at mutual friends' houses and we'd developed into a "fling". He knew about Josh (and had actually met him months prior) and never seemed bothered, so we continued hooking up and expressing interest in each other.

Mason started acting a bit weird towards me within the last few weeks and it brought me a lot of anxiety. Josh and I had recently (within the last 3 months) become nesting partners, so it was hard to taper my feelings of anxiety about it and I knew it was affecting Josh. We had long talks about NRE and what it would mean if Mason and I ended things, or even if Mason wanted to escalate. A lot was up in the air and I felt bad for echoing my anxiety to Josh.

Well, Mason and I are no longer seeing each other due to very terrible circumstances. A very close member of his family passed and his mental space for anything more than family is limited right now. Of course I feel terribly for him, and I (albeit selfishly) am a bit sad that I can no longer see Mason. But I know it wasn't anyone's fault and I continue to maintain a distant friendship with Mason while he grieves.

I've just been having a tough time with Josh trying to rewrite boundaries around NRE and new partners coming into the mix. Josh feels that I've had a lot of bleed over and that it's not fair that I go out and have these euphoric experiences with Mason (festivals, parties, etc.), and then come home and experience a come down when I'm with him. Because of my intense feelings towards Mason for a short time, Josh worried that I'd change my stance on non-monogamy and leave him. These are all valid fears that I completely recognize.

I guess I'm just venting about how icky I feel to called out for something I also went through not that long ago. He did a lot of the same things back with Leah, and I never made him feel bad for it. I've been trying to take it as constructively as possible, but I guess the emotions of the situation has taken me over. I'm not trying to say that I'm better than Josh or the good guy by any means, I'm just dealing with a lot of feelings from both ends with nowhere to vent. Thanks for listening.