I want my physics instructor
In what way do you want your physics instructor?
I'm want to be with him until death.
Crushes can happen even with teachers or other people we look up to but you don't have to do anything about them. Especially if they are a teacher since it could get them fired.
If I don't do anything, I'll never find someone who wants to be with me. What am I supposed to do?
That's not true at all, you could find plenty of people to date that isn't your instructor. You should do that and avoid all the messiness.