I fantasize about my professor constantly
What makes you think that you like her?
I think she's pretty fine and I wouldn't mind spending the rest of my life with her.
It sounds to me like you are infatuated with your professor. This is normal, as long as you don't act on it.
What can I say? I like women with long blonde hair. I'm going to take her out on a date and then plow her later.
People would think it is extremely wrong of you to act on those fantasies, but otherwise there's nothing wrong with thinking about them from time to time.