I think the teacher has suspicion to believe inuyamas relationship is going to affect his art. Can't say I don't understand him. Inuyama is driven by horniness and his art is a reflection of that. The fact that he's trying to surpress it will in turn affect the quality of his work.
I kinda doubt that is what the teacher is thinking. like all he notes is that Inuyama is fidgeting, what could mean he notices the feelings between his students