Also gotta say, this girl has bad taste in romantic partners. I mean I'm one to talk, like jfc, but I'm currently not enamored by this dude lol.
It's not about "this dude", he's just conveniently there.
As for his behaviour, I'll fully agree his way of interacting with his student is inappropriate... But entering a romantic relationship with them is actually much worse, and it applies to literally all and any story with these tags, so I don't think he's particularly worse than the other generic teacher characters in these stories.