I've been single now for 2 years, and for some reason, people think I should be very depressed about this. I'm not of course. And I don't really think "when is my next relationship going to be??"
To more directly answer your question, as strange as it sounds, if I knew that in the future, I'd never find someone again, I'd be ok. I don't actively seek relationships (i.e., go to places for singles, or try to meet people online), but I'm very open to a relationship if it comes my way. People seem to think that you have to go "looking" or else, "how will it happen?" but my experience has always been that, when a relationship is supposed to happen for me, it happens.
Maybe your feelings are a sign that you should work harder on 1. being happy as you are (single) and 2. not focusing so much on the future
Don't worry about it so much