teen ager being companion to a dying girl not good for him.?

It was ok for the mother to suggest strongly in the beginning that Greg should visit a sick classmate, but didn't she know that he was spending way too much time with her to the detriment of his schoolwork and getting into college? It's not like the girl was already his best friend--he hardly knew her before she got sick. The situation was too hard on a sensitive teenager who couldn't handle it. I felt it wasn't in his best interest, and the parents should have intervened. Sorry if this sounds hard-hearted, but most teens aren't mature enough to handle this. I guess if he had not had problems with his schoolwork I wouldn't feel this way , but he got so depressed he was flunking out. Also, the school advisors seemed to know about this, so why didn't they step in?