I read the title of your thread and even said "YUP" out loud. Always felt like a misfit for my whole life, rarely feel comfortable around more than a few people at a time. Sorry if this reply gets long as hell lol but it resonated with me and I didn't want to see this get 0 replies.
It's hard to vent about this because people who don't get it, can't wrap their minds around it. They just blame me and think I'm not putting in the effort, that I'm looking to be coddled, that I'm too self-centered, etc... But the truth is that I put a HUGE amount of effort into trying to belong. Changing my personality to match the group dynamic and aesthetic, code-switching with them, being down for any activity they want to do. Being ready to drive out to help them or lend a hand/dollar when needed. Getting them gifts, remembering things they like, everything... And I've done this for lots of people when I volunteer, work, join activities, everything.
But... it's just never enough. Nobody fights for me, nobody really tries to get to know me. At best there's an initial honeymoon period of "omgg I literally love you we're meant to be besties" then things just cool off and, like you said, I remain the outer layer of the onion. I'd say "the friend that gets invited to the club but not the Applebee's trip after" but I don't even get invited to the club lol. Is something about me just off-putting? I tone myself down as much as possible, I'm hyperaware of what comes out of my mouth, but nothing works. I just end up feeling like a bigger freak. I think of a quote from an old Buster Keaton movie: "Some people go through life making friends wherever they go... And some people just go through life."
I don't think anything is wrong with you of course. Probably not even me. There's just so many politics and history in most friend groups that it's tough to make it. And like you, I pull away and isolate myself when I'm not feeling accepted which of course makes people assume that I didn't want to be there in the first place, or I'm less trouble if I go... It's tough. I really wish I had that social media kind of friend group, that ride-or-die band of besties who go everywhere together and do everything. I'm lonely as hell honestly. At least I make good company for myself.
To answer your question, I think friendship IS possible through this forum. Not everyone is out here ready to die within the next week. It's tough to navigate the minefield of trying to find out who's a scammer, a fetishist, needs more help than anyone on this forum can offer, thrill seekers, whatever, but there are plenty of people here who aren't in immediate crisis and who would be helped with a sense of support or even just someone to talk to regularly. Off-topic and Recovery sections are likely the best bet for a connection.
Again, I don't think anything's wrong with you, unless you're of the variant of people who are like, "I don't understand why nobody likes me, so what if I stole their microwave when I was at their house/slept with their partner/sold their great-uncle's ashes for heroin/keyed their car because they left me on read/came to a fancy dinner in a full fursuit. But I have a big heart, I'm such a nice person!" but I'm not getting that vibe. There are some downright abhorrent gnomes in the world with a tight group of besties and ride-or-dies. The challenge of course is finding your tribe, and it's tough as fuck, I hate it too. But there's billions of people in this world, if you want to look for them. To wit: I've paid hundreds of dollars over the years taking classes and joining clubs to try to find friends as an adult. Gone to concerts, local events, everything. Nothing. Then I started a fanfiction in 2023 on a complete whim, and a girl kept commenting on it. Now we talk every day 1x1, we met irl and we're going to Japan together on a group tour in the fall. Sometimes, if you build it, they will come. Life is random and weird as fuck.