It's perfectly normal to think you're in love, to believe only good things happen, and life always turns out for the best.
It's perfectly normal when you are wondering who and what you are to bloom when someone who says you're special, that they agree with you, and understands all the problems you face.
It's all perfectly normal - when you're fifteen. As we get older cynicism seeps in like damp, and most of the business of adulthood is stopping it taking you over completely.
Having a pash on a teacher is almost a rite of passage, regardless of your gender or your school. Even if sex isn't involved, there will - if you are lucky - be a teacher you look up to, want to please, and earn the praise of.
It's a normal part of growing up to slavishly admire someone other than your parents who by that point in your life seem as boring as hell and want to keep you subordinate. Teachers who treat you like an adult are not only appreciated, they're a vital part in you becoming an adult yourself.
I fell in love with teachers a couple of times. One was young and absolutely beautiful and stood out among the ranks of middle-aged men with dandruff, and I would stare at him for whole afternoons and not hear a word he said. Another was very clever and treated me like his star pupil, so I wrote awful poetry and moped around after class.
Nothing ever happened with either of them, because I was the kind of teenager with braces and NHS specs who found the world was much nicer if viewed from behind a curtain of hair and a book. I spoke only in grunts and when I was in love I made no sound at all.
But at that age love explodes like a bomb, whereas when you are older it is something you negotiate. One is indiscriminate, and the other is very discriminating indeed.
Teachers know all about that sort of thing. Apart from the ones with really bad dandruff they all get it at some point and most can differentiate between a favourite pupil who stands out more than the others, and a confused, hormonal child who can be led to the bedroom.
There is always one who can't, though.
Megan Stammers disappeared last Thursday along with her married teacher Jeremy Forrest, who was under investigation by education bosses. They seem to have fled the country to France before the authorities could uncover their seven-month romance and put a stop to it.
Police and their families want them home safe, and there are people all over the country saying "well it's not kidnap" and "she's almost an adult" and "we've all been there, haven't we?"
Well, we've probably all fallen in love with someone we shouldn't have, but how many of us ran away from home, broke up a marriage and went on the run?
Not many. It's extremely unusual, just as it is that a 30-year-old married man thinks it's reasonable behaviour to take a child put into his charge by her parents and skip the country to escape the consequences of his actions.
And his actions, when you look at them, are shattering.
Jeremy Forrest was in loco parentis - he was paid by the state to look after children and teach them things their parents couldn't. He has destroyed that trust not just in Megan's case but that of the hundreds of other pupils potentially in his care.
He enabled a child to leave her safe and happy home, causing the parents who have cared for her since birth unspeakable anguish and worry. There's a bed that's not been slept in for five nights as her family can't sleep or eat and jump every time the phone rings.
He has persuaded a child into an inappropriate relationship. Whether it is sexual or not is almost neither here nor there - the potential for Megan learning the wrong things about how men and women, adults and children interact is enormous.
It would be easy to draw parallels with high-profile relationships, like Michael Douglas marrying a woman 35 years his junior, any of Rod Stewart's affairs, or 32-year-old Caroline Flack dating a 17-year-old Harry Styles.
But Flack wasn't his teacher, nor did she help him run away from home. Catherine Zeta Jones is an adult with the experience to know when the man she's with is acting reasonably towards her. Rod Stewart has done his share of inappropriate things but never, so far as we know, with a child.
Jeremy Forrest's job is to teach Megan and children like her how to think for themselves, with a side order of keeping them safe.
Yet the only lesson she's learning is how to upset a wife, how to distress her parents, and how to put yourself under the control of someone who's not worth the trust placed in him. She's being taught how to run away from problems, avoid consequences, and put her faith in fantasy.
It won't last of course, because they'll be found eventually, he'll be sacked, the police will get involved and his wife will want some answers.
Then Megan will learn what heartbreak feels like, how you can never take things back, and how long hurt can last. She'll feel sorrow for her parents and embarrassment among her friends, and if she's sharp she'll see there's a difference between schooling and grooming.
Forrest probably won't. He will more than likely continue to put his feelings before others', be a slave to his hormones and think that he's perfectly normal when in fact he's trying to keep hold of his own youth by stealing someone else's.
Which is perfectly normal - for a paedophile.
There are no practical lessons.