Many, many people get crushes on their professors or tutors. You get to see them at their absolute best: teaching a subject they love! The professors who are reasonably good-looking and talented at what they do must get a dozen students with crushes on them every semester. If he is a good professor, he will pretend he doesn't notice. It can jeapordize his career to pursue romantic involvement with a student. It is considered unethical due to the power imbalance, and besides, he is probably married or involved with someone.
I think if you can't get over your crush, you should consider finding someone else to do your master's thesis with. I've seen lots of women humiliate themselves over these crushes.
(Ironically, if you could meet these professors outside their teaching environment, you would probably find them much less interesting.)
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?