Confused FeelingsMovie

It is the story of a middle age professor who falls deaply in love with a young student in his English literature class. The student is a boarder in the teacher's house. The teacher is married and his wife knows he is mostly attracted to young men. She loves him nevertheless. The whole story revolves around a book the professor will write, dictating to his young pupil... he will only declare his love at the end of the writing ...and, it is too late.