Life long teenage sweethearts are an endangered species according to findings which turns the spotlight on the differences between the generations, writes Tom de Castella.
Childhood sweetheart - the phrase conjures up something magical, a relationship defying the usual scientific laws. Even when estranged - think the film Sweet Home Alabama - there is a metaphorical glue that pulls them back together.
Romeo and Juliet's star-cross'd lovers are the apotheosis of this ineffable, pure passion.
In real life, childhood sweethearts don't have to be killed off, or separated and reunited. Think Jamie and Jools Oliver, Wayne and Coleen Rooney, Jessica Ennis and Andy Hill (long-term sweethearts who married in May).
But research suggests that these relationships are becoming rarer. A study by the Co-operative and The Future Foundation, says that just one in seven of middle-aged couples have known each other since their formative years. That compares with almost a third of couples aged over 60 who got together as teenagers.
The bar-room philosopher might have several hunches. People marry later today. Many more young people go away to university. Personal development has replaced settling down. More people meet at the office water cooler today than smoking behind the bike sheds.
And we're fussier. "At one time we felt we weren't going to meet anyone different or better," says relationships expert Judi James. "We swim in a bigger pool these days."
Life is a smorgasbord of options. Brief Encounter the movie - in which duty won out over lust - has been replaced by Illicit Encounters. There's not just a menu of different dating sites. Apps like Grindr, Blendr and Tinder offer casual hook ups for passing strangers who might take your fancy.
Today life is about change rather than stability, James argues. "We travel more, change jobs more, we feel we should be experimental with our relationships."
And perhaps there's a double standard at work. We may love the idea of childhood sweethearts. But in real life, do we really feel awe or something else - pity, even. "Saying you've been together since school is a bit like saying you still live in the same place you grew up."
Before we all get too cynical, let's check in with that unlikely pin up for unrequited love - the Pope.
We don't know how true Amalia Damonte's side of the story is about her friendship with Francis or Jorge as he then was. But it still flicks a switch when she talks of how at "12 or 13" the future Pope wrote her a love letter: "It said we were going to get married and I am going to buy you a white house. So the two of us could live together. He said that if I didn't say yes, he would have to become a priest. Luckily for him, I said no!"
Whether or not young love works out, that first crush is something people never tire of talking about.