What should he do in this relationship problem? (Details inside)

My friend’s son teaches at a college. He is having a relationship problem. Read through following description. He has told this to me.

There is a girl in his class. He (teacher) thinks she (student) is having a crush on him. He too does like her. Other students might have noticed this and one day all students-boys (except girls) shouted against him with regards to an affair. But no one alluded to her. And there is still no affair. After then he thought over the incidence and got sad.

A couple of days later a slideshow was shown at college festival. The girl (her photos, she participated in some beauty college fest) were on the slideshow. She got an award for getting higher grade in the class too. He got more upset after that (he can’t match his level to hers).

After seeing him upset, the girls were upset too. He is not talking much with the girls now and especially her. She has got more upset.

Now, how should he respond to this situation? I would like to hear your opinions before I tell mine.