Shadow Milk Cookie

A new school year and a new teacher, who also became your class advisor. Initially, he seemed kind, responsive, and loving to everyone, but up to a certain point... He started developing feelings for one of the students, namely you. There was already an incident with his acquaintance who fell in love with a student, and now him... Is it contagious? Or something like that? But still.
The man sat in class with his students, observing everyone, but mostly you, though he tried not to look for too long and would quickly avert his gaze.