To be honest, relationships aren't for everyone. There are some people who feel better just being on their own. It happens, and that might be what you want to do. You can always change your mind later if you want to.
That being said, it might just be because you haven't met the person who will let you be yourself yet. I don't know how long your relationship lasted, but part of the problem might be that in the early stages of a relationship it's easy to get stuck into that feeling of "omg I have to do everything perfect or I'll lose them" kind of thing. Once more time passes you get sick of it, you fight over it, but then you talk with your partner and figure out how to find a balance so that neither of you will feel pushed around all the time. It's rough getting to that point, but if both of you are committed to communicating, compromising, and working out the problems, I think you can get to a state where you're not waiting around on your girlfriend all the time.