The realization that I don't even remotely miss her really bothers me....So even if she decides at some point in the future (and it really can't be that far, I don't know how much patience is really left) that she wants to be married to me, I'm not sure I can say the same in return. How do I deal with that?
Hmmm.
I believe that at some point, probably not today, your goals for your future will become clear to you. And how to reach them will become clear to you. And then it will be clear.
But it can't be forced, and to fear it usually means to avoid/ignore/hide from it. With whatever self medication you choose.