I.... don't trust the teacher at all..
I have read this trope so many times before I think Hirose have a bit of a crush on the teach but as we can see he still likes girls so him liking the teach gives us hope that he (also) likes guys so basically our Nakamura will have a chance on him. But this is just my opinion from all the past BL I've read ┑( ̄Д  ̄)┍
Jin, for the love of god go save your boyfriend from that psycho