It isn't fair to punish people for other people's mistakes. It's hard, but if you don't want to spend your life alone and miserable then you don't have much of a choice.

I'm similar to you in regards to the fact that I am 30 and I do not drive. If I wanted to go to the part of town where I could DO something, I would have at least a 45 minute walk. Which is about a $10 cab ride. I'm also quite convinced that NO ONE will ever stay around for long. But I still make myself give people a chance - it scares the crap out of me, but I do because it isn't fair to them and if I start out assuming that everyone will hurt me the same way, well, then I would be alone all the time.

Instead, I put myself at risk every single time. I do have some very good friendships because of that. Does it mean that they won't end up eventually hurting me in the same way? Nope, it can happen. Or maybe it won't.