How do I be okay with being not as close to my best friend

Hey so I (21M) have this really close friend (21M) that I met at the start of uni 3 years ago. So for context, we’ve had a similar problem around 2 years ago, because he started sorta distancing himself and I called him out on it. We pretty much had like a massive argument over it for about 6 months and honestly after I had reached the point where I was ready to cut him off, he apologised and we because REALLY close afterwards. He’s a bit adamant on the fact that he doesn’t do “best friends” but then the whole of last year, we were pretty much inseparable and were that, just without the label of being best friends I guess.

So the problem started at the start of this year, when I noticed he was sorta distancing himself again, and I asked him about it. He said he wanted space to branch out and meet people but if it felt too off to let him know. I was fine with that but it started getting to the point where we would just never hang out, and if I wanted to hang out I had to rely on my other friends inviting me to plans he’d made with them. That along with the fact that he became more closed off and our conversations changed made me feel like he was slowing cutting me off again. I would ask him to hang out or to just simply tell me if he was coming to uni, and he would just never tell me or would just never hang out with me. I got a bit jealous because he would be doing the things him and I used to do with other people, like he practically replaced me.

I got so sad about it that I just stopped talking to him, and that annoyed him because he thought that I just couldn’t handle distance and it made him feel like if he made new friends, I’d leave ( Which I have never insinuated, the closest thing to that I’ve said is that it feels like he’s replacing me). Anyways we talked about it and mutually decided to avoid each other for a bit and see how it goes.

We ended up doing that for a month and we started talking again to figure out a solution but then things happened and we sorta just became “friends” again, in that we had exam season so he just called me whenever he was tired or needed something and I would be there. Now exams are over, and I need to figure out what to do because it just feels off. I don’t enjoy the conversation like I did before because he’s become more closed off. And the person he replaced me with (I’ll call him B), I’m close with him too and the only times I’ve hung out with my friend he’s been there too. What’s so sucky is that when I hang out with the both of them, it feels like he doesn’t want me there. Like he would just look at B when talking, make jokes just with B or just ask him questions and pretty much ignore the fact I was there until he realises and makes a half assed joke. It’s especially shitty cause B keeps me in the conversation and does the opposite of everything I said my friend does.

I need to be okay with the fact that he did replace me with B and if I be friends with him, I’ll just be like a background friend, not someone he’s close to. I’m finding it hard to be okay with that and it makes me feel shit every time I think about it, but I can’t cut him off either because I will see him often because of our friend group. What do I do?