It's a work of fiction, there are going to be things that are overblown for dramatic effect. The unnesecary involvement in the students lives is quite literally our main motivator to dislkie the homeroom teacher other than that she's just a run of the mill judgemental person.
like I understand your thought process here, but what are you expecting. It's your classic romeo and juliet style story but with schools. And it isn't even that far fetch in the right enviroment. Hyper religous private schools with no dating policies exist which are enforced irl because they praticaly get people to snitch on each other. (I actually have a friend who went to one a few miles away and they got expelled for sharing a motel w someone while on a trip, and I'm sure you can find many more stories from other people online let alone evidence of that general behavior)