Nani?! My opinion is on the complete opposite. Sensei had such a bad start with Makoto, harassing her at her family shop, blackmailing her with compromised photo, you name it.
Compared to other girls, even when Sensei was deliberately tapping the girls' weaknesses to get his dick sucked, he sometimes still brought positive impacts to the girls, whether it being intentional or not. And I don't see that at all for Makoto. If anyone would benefit the most from "graduating from Sensei", it would have to be Makoto. She deserves better. A lot better.
Where she was and where she is now make Sensei x Makoto worth following, but "healthy" is not the word for it.