How do I know if relationships are possible for me?

Basically, I'd just like to know if there are any things that people who've never had a relationship, sex, etc, do, or are, or have, or any other characteristic of them, that distinguishes them from people who do get in relationships, have sex, etc. I'd rather not just keep "putting myself out there" and feeling like an absolute husk of a person when nothing happens, if the heuristics say it isn't possible.