When I first met my partner of 4 years, he had a female friend who he had dated in the past who took the start of our relationship v.badly and made things difficult, despite him describing their friendship as platonic. There's another woman who is friends with both of them (has known my partner a long time, they lived together for a while and briefly dated). When we'd cut ties with the first woman at the start of our relationship, a couple of months later my partner said he wanted to spend time one weekend one-on-one with this other female friend/ex who he also describes as having a platonic friendship with. I've never met her and after the previous drama with the other woman, I made it clear I wasn't too happy about it.
About a year ago, I found out he'd met up with her anyway but didn't disclose it to me at the time. He got very defensive and shouted a lot. When things calmed down, I explained that because of the situation with the first woman when we first met, it made me question his judgement of whether his friendship with his other friend/ex was platonic. I said I would feel much happier about the situation if he could organise for the two of us to meet his friend together (I've never met her). Then I could perhaps get to know her and would feel better about them spending time together one on one. He said he'd try to organise a date but then immediately sounded like he was prepping me for disappointment, saying things like she doesnt like meeting people, she probably wont be able to afford to go for a drink etc. In the end, we never met.
This afternoon, my partner casually dropped into conversation that he's planning on seeing her for a walk tomorrow. Now we're in lockdown, it would just be the two of them.
Aibu to feel upset about this? I dont believe there's anything going on and i'm very sure there arent romantic feelings from my partners side. But from experience, I think he can be naaive to other peoples feelings and what with never having met this woman (and him seemingly not wanting to organise for us to meet), something feels off.