I've (F30s) been seeing an old friend (F30s) for a few months. There's some distance between us so we only see each other monthly. This person has another partner (M30s), who they have been with a little longer and see much more frequently, while I'm currently not dating anyone else.

When we got together, she told me that she didn't want to rush into sex immediately and wasn't feeling particularly in that headspace. That wasn't a dealbreaker to me, I have my own issues and have gone through periods of low drive so that's fine, plus it was phrased in a way that implied that this might be temporary/fluctuating. Except...when we next see each other, she casually mentions something that implies her and her other partner are having sex. This is then confirmed to me at a later date when I find condoms by the side of the bed - I have to stress, I wasn't looking for these, they were in plain view, where she knew I would be. I also found what I believe to be a charger for a vibrator (it looks the same as mine). Now, I am not upset that she's enjoying these things. I don't want her and her partner to stop. I'm perfectly fine with her other relationship existing and being good and nice for her. I'm happy that she's reconnecting with her sexuality. I'm upset because I feel that I've either been lied to, or, maybe worse, that she was specifically not in the headspace to have sex with me. As it happens, since being with her I've actually found myself incredibly trusting and open to the idea of sex, more so than I would have expected, and actually started to feel guilty for being turned on around her at the beginning. The last thing I want is to be some horny. pushy creep. I just want to share more closeness with her.

On top of this, I've noticed some emotional distance/unavailability in the last few weeks, and have had to lean on friends more than her, as I've been having a tough time. During these talks with friends, when I tell them about this relationship, they express concern and, sometimes, almost seem angry for me. I'm terrible at standing up for myself, have poor self esteem, and they seem to think I'm getting fucked over or selling myself short by going along with this. For me, yeah it's not ideal, but I do love this woman and I don't expect her to meet all my needs. But I must admit it's starting to feel less like I'm in relationship and more like I have a friend I cuddle and make out with sometimes.

The obvious solution of talking to her probably isn't going to work, as my attempts at direct, vulnerable conversation seem to overwhelm her, she expresses a desire to engage with it at a later date but then it doesn't really happen. I'm starting to feel that things are quite one sided, everything seems to happen on her terms. I'm an accommodating person, but I'm just not sure if I'm getting what I need here.
I could also try to date someone else I suppose? Feels a bit petty honestly, plus I have no one in mind and am not especially confident about my attraction skills. I'd sort of rather have a secure relationship in place before I start dating anyone else, rather than juggling a bunch of vague and ill-defined connections at once. So I don't really know what to do, and I'm worried that my friends are right and this is another one of my classic delusionships where I feast on someone's crumbs for as long as I can stand it. My friends aren't as experienced in polyamory as I am, though, so I wanted to see what you all think about my situation. Thanks if you read this!