Not to be the critic, but what if it's not true?
I mean, after watching 10 episodes of Great Teacher Onizuka, I can't help but wonder if a student could've just forged a "love note" and the teacher resigned.
And teachers do resign. My principle resigned immediately after being accused of participating in a homosexual orgy at a highway reststop by police officers. He told me, paraphrased, 'If I resign, people forget in 4 years. If I make a fuss, the media gets involved, the school looks bad, and the reputation will follow me to every other job I seek.'