The matter at hand is complex and controversial. There are beautiful poetry exchanges between the teacher and the young pupil, of whom we learn he is of age; there's clearly genuine affection and not just grooming (by the way, grooming in general is used not only when children are concerned). On the other hand, we learn that the teacher has taken advantage of - literally abused - other students who fell under his spell and intimidation. The other points are that there wouldn't be an issue were he heterosexual and abused girls; he would be praised for his machismo. Particularly harrowing is the ordeal of the boy who is forcibly institutionalised by his family and damaged through electroshock "treatment". I'm not sure where the director stands on this - on the one hand he portrays the accounts of boys who testify they were abused and even contemplated suicide; on the other, there's the tone of advocacy throughout - a fervent plea against the stigma on homosexuality, as if this were the only issue.
Aesthetically the film could be stronger; there are stretched episodes where not much is said or happens, as if we're supposed to get into the drama of the different characters intuitively - but they are given no background and remain vague. The forte is the poetry exchange and the ordeal of the young man, crippled and abandoned by his family. We learn he's also abandoned by the teacher, "the only one who cared" in his words.
P. S. On a second thought, poetry may be a sure form of grooming.