No matter who you are, being in a long distance relationship (LDR) is another level of commitment. If you have doubts about the relationship you are in, an LDR probably isn't for you.
I don't mean small, general insecurities about the future. Specifically, I am referring to the possibility that you have ideas about the person not being "the one" for you. This is very important, because who wants to commit time and energy to an LDR that isn't founded on mutual long-term intentions? Really, that's a bit masochistic.