living in a place with no community is a hell in and of itself. People who just click in with society easily get access to a bombardment of new people and potential connections. I'm convinced that most people who have relationship problems, even those with mental health issues like myself just don't have access to enough new people to potentially connect with. After high school ends it's a wasteland, and depending on the geography of the high school it might have been a wasteland there too.
Here's some hope for you anon, if you want it. I was in the same boat for my whole life until this past year (am 22) when I met a girl through a mutual friend and we hit it off. Keep in mind I've only been friends with 3 girls my whole life and 2 of them before puberty (sadly don't talk anymore.) Lo and behold the 4th one I met wanted to be more than friends and things worked themselves out. We both have mental health issues but work with each other to get better. She cuts, I'm paranoid and have bad panic attacks. My paranoia has gotten better since being with her and she hasn't cut in months.
Whatever social outlets exist for you, if any, try to branch out beyond them. Being around the same people is great and all, and you should pursue life long friendships if people are chill and you want that, but the average social group only lasts 3-5 years and if it's not doing anything for you branch out. This can be online too if you don't go outside. I've had 3 online friend groups in the past 10 years and excluding a few keepers from them all they've all fizzled out.