???

It's not necessarily coming out of nowhere (doesn't mean it's right or should have come out) with the teacher he acted jealous and was a bit out of line, the student who had a crush on Naoto, even with the preson who graped Naoto he was acting jealous. I think the author was trying to show that the line will keep being pushed until they do something that's going too far

Omg you’re so right I never noticed the jealousy slowly becoming more and more toxic :c