Sarah Sands: First love is best left in the past, unmourned

Fame creates an aura of association. The name Steve Blacknell means nothing to me and Kate Bush will leave most people under 40 blank but, if we say the first boyfriend of the musical predecessor of Florence Welch, we are in business. Blacknell is selling a teenage love letter from Bush, claiming that he is the subject of her song "The Man with the Child in His Eyes".

The eBay generation points out impatiently that Blacknell has a lousy sense of timing. Why didn't he flog the letter when Bush was famous?

The sale and the timing suggest two things. Blacknell could use some cash but is neither greedy nor vengeful. If anything, his crime is sentimentality. Aged 58, he has the glow of recall and the bittersweet awareness of the passage of time. When he met Kate Bush they did not know how their lives would turn out, which ambitions would be realised, which hopes dashed. We know that age improves the longterm memory and Blacknell's relationship with Bush may have been the most acute phase of his life.

I have just been reading Candia McWilliam's self-flagellating memoir What to Look for in Winter. Instead of time healing, it blisters and weeps. McWilliam, who becomes blind, is in love with her former husband. The past was the best.

We assume that relationships are evolutionary but that cannot always be so. The reason first love is so romanticised and written about is that the raw heart may also have been the truest. There is no calculation, only passion and hope. As John Clare wrote in his much-quoted poem "First Love": "I ne'er was struck before that hour, with love so sudden and so sweet." After that many other things strike you, such as tics, a weird family, snoring or a lack of any common interest at all.

It is a terrible mistake, I think, to sentimentalise old loves. McWilliam notes wryly in her anguished and brilliant account of the past that her loved and lost husband, Fram Dinshaw, always skips the childhood section of any biography or autobiography. I think he is coolly right. Personal narratives become plausible only once they are on solid ground. McWilliam deals in ghosts, especially when she says: "I hanker for the innocence that was the world Fram and I had."

Recollection of first love should be civil and detached and equal. When David Cameron became Tory leader, a delighted Mail on Sunday journalist, Caroline Graham realised that it was the same person that she had kissed when he was 13. She got some news copy out of it, and it did the future Prime Minister no harm to be described as an "expert kisser". No broken hearts there.

Similarly, I remember Rachel Johnson, the writer, quizzing the BBC's economics editor, Stephanie Flanders, at dinner about her old flame Ed Balls. Fascinating for the rest of us, except that the Financial Times is clearly a breeding ground in many senses and neither Flanders nor Balls regretted the way life had turned out, so the revelation lacked surprise and poignancy. Early relationships are more potent when they suggest an alternative destiny. Was Tony Blair actually better suited to his earlier crush and later aide, Anji Hunter? No wonder it drove Cherie Blair bonkers and provided such an intriguing subplot for Robert Harris in his novel The Ghost.

What if? The most intriguing question in the language. First loves are based on possibility, not realism, and have an exquisite fragility. They can be Romeo and Juliet. Or, in baser life, Kate Bush and Steve Steve.