The second I start liking someone even a little my mind jumps to, 'okay... but will you ever like him enough to be with him and only him forever...

Because of this very thought pattern (and others, such as "what do they see in me" and "I have no idea what to say or do"), I never dated anyone until after high school. In my mind, I would always skip the entire relationship and jump straight to the end, and then conclude "it's not worth it."

And maybe it wasn't, but the point is I don't know.

We don't know (except when we do).

We can't rely on our mental relationship simulators to give us accurate assessments. Love doesn't work that way. Not the kind that keeps people together. It has to do with synergy and emotional understanding and following intuition and free will. It has to do with people's growth or lack thereof, relative to each other.

I think it's too hard to find one's soulmate on one's own. I've chosen to stop worrying about it and trust that when I'm ready, we'll find each other. In the meantime, I'm enjoying growing into who I want to be.

Anyway, I doubt many relationships can survive the early assessment of an expectation of its demise. So it's probably just best to follow your gut and not try to figure it out in your head.