What you have, my friend (if I may so address you) is a vocation. Your devotion to your students and to teaching shines through everything you write. I hve known people have the same 'problems' with relationships that you do. In every case it was because they had devoted themselves to something else: a cause, a belief, a vocation. They gave so much of themselves to whatever it was that there would never be space to completely belong to another individual. There was always a part of them that was out of reach to their Significant Other.

Nobody who doesn't have a vocation can cope with that, and those who do would not intrude on yours.

It's who you are. Don't fight it, don't worry about it. You achieve far more as you are than you ever could as part of a relationship.