@boag Remember that the story is fictional and chill some, even if this situation would be reprehensible in real life due to the psychological and emotional damage alongside the feeling of being trapped in real life, those aren't necessarily true in a fictional story. I'm not condoning the actions but expecting realism in any sort of porn comes off as a tad silly to me, especially when you are ignoring what the fictional world is establishing as rules. First of all, the guy DOES care about her, he got her a phone, has tried to understand her life, and when she needs his help he helps without hesitation and doesn't put strings attached, sure as seen here he does try to get sex while there but given how she was able to dissuade him from a round 2, how he didn't require her to promise anything beforehand, and how he's being roughly 80-90% honest with the teacher we see that he's not trying to force the issue and if she was firmly against it she could have stopped it (I got the impression that the author was trying to communicate she was more uncomfortable doing it there at first just like someone might be uncomfortable skydiving for the first time or singing in front of friends or something).
I get that it may not be for you, but given that the teacher seemed to legitimately think the guy was good for her and not just 'better than homeless' (implied by how he complimented the way the guy was taking care of her, even if indirectly, instead of giving advice or voicing concerns) it crosses my mind that if you can't suspend your disbelief about their relationship, then you would probably be better off staying away from this one. Most pieces of fiction have an entry fee of what you need to be willing to go with, and their relationship is what this requires of you.