I can’t really advise on “how” to make friends, aside from maybe look for groups (hobby type - my iPad nearly wrote hobbit for some reason! Or sports, etc. Something you’re into maybe and would like to share with others. See who you get talking to etc and take things from there).
What I really want to ask is do you know anything about attachment theory? Your dating experiences sound very similar to mine, except for the fact I was more often the dumpee than the dumper! But I know that I have attachment issues which did/do cause me to get stressed out in relationships, even with ‘just’ friends on occasion. That’s just something I think you might find useful to look into, not a diagnosis as such.
I wouldn’t say I didn’t want to be with any of my boyfriends, but I did feel trapped quite often and had that “this will end” feeling you described. I was more scared about what was going on, because I was just confused so much. There was rarely any feeling of connection for me.
All that said, if I had to live my life over but could make different choices, there’s only one person I’d still choose to date out of everyone I got with.