A married, 30 year old teacher should know better than to run off with a fifteen-year-old girl in his charge. It's my experience that by their late twenties most men are able to limit their libido with the knowledge that their actions might have consequences (this is not universally true, obviously).
Far be it from me to prejudge matters but I think we can all see how the script will go. The man's life is ruined: his jilted wife will ditch him; he'll probably face jail time; he will be on the sex offenders register and will be unable to do any work involving children (including volunteering) at any stage in the future.
His Facebook page given above is revealing: 'How do we, and how should we, define what is right or wrong, acceptable or unacceptable?' Well, traditional morality, the Ten Commandments, the established norms of a society and not running off with teenagers might be a good start.
Funny how the Dictatorship of Relativism has tricked the man into thinking his moral choices are somehow OK and that he's a 'good person' underneath it all and yet now the same society which paints these ways of defining morality perfectly OK will take him and try him and pillory him as a nonce.
He will have plenty of time to consider the fact that 'look[ing] yourself in the mirror and know[ing] that, under all the front, that you are a good person' is not really a solid way to organise your moral life.