I adored him, I wanted him, I couldn’t bear to live without him, except that I could, and I did. Once I went to university, we lost touch. Soon after uni I met my gorgeous husband, fell in love (properly this time, and with someone who liked me too) got married, and had three children. Willie, the rascal, became a dim and distant memory. Until three years ago when I went to a dinner party in Abu Dhabi, where I live.

The dinner was hosted by a friend of my husband and his Venezuelan wife. We were just moving onto coffee and chocolate when the host said: “Try this, it’s made by my best friend Willie.” I almost fell off my chair. I had of course vaguely kept up with Willie and his chocolate adventures. This was after the Channel 4 documentary about him and his dream to bring real chocolate to the masses, so I knew immediately it was him. As did my husband.

“Oh, Chocolate Willie, he’s an old friend of my wife’s,” my husband said.

“How amazing,” his friend said, “we’ve known him for years, he’s one of my very best friends.”

They proceeded to bring out photographs of them with Willie, taken mainly at his finca in Venezuela. There he was, my first love, grinning at me next to these two relative strangers in some faraway land. The whole thing was surreal, at one stage I had to go to the bathroom to gather my thoughts.

For some reason I couldn’t stop thinking about how odd it was to have come across him again. They told me he was married and that he had three children. Then a few weeks after the dinner party, they said he was coming to town.

“You must both come to dinner again,” the wife said. “It will be fun.”

On the night of the dinner Stevie Wonder was in town and my husband already had tickets to that, so I went off to meet my first love alone. I felt ridiculous. I had butterflies, like some idiotic 16 year old. I couldn’t decide what to wear and half dreaded the whole thing. But I couldn’t keep away.

When I got there he was upstairs.

I nervously gulped down a cocktail and tried to come across as terribly nonchalant. Then suddenly he was in front of me, telling me how good I looked. The whole room and everyone in it except for him seemed to vanish and I was catapulted back 20-odd years to a bar on the King’s Road.

At that moment I honestly felt like nothing had changed. I was the silly little girl I was back then.

Happily I made it home, alone, without rekindling anything with Willie, not that he offered. But what remained was the feeling that this first love thing is so strong and so powerful that I wanted to write a book about it.

I felt sure there must be lots of other women who feel the same way I did.

Joan Didion, the American writer, once said: “I write entirely to find out what I’m thinking.” I most definitely do the same, and I write to get things out of my system. I should have written a novel about first love years ago, it has been an utter revelation.

In my book, The Ex-Factor, Marina is a journalist who writes a column about first love and through that gets in touch with her version of Willie, a photographer called Tom. She writes about how we imprint on our first loves, and that is one of the reasons they are so compelling. I am thrilled that I didn’t end up marrying Willie. I would have been obese for a start with all that chocolate to taste and we really have nothing in common apart from a shared youth. I have been extremely happily married for almost 15 years and my husband is still my best friend.

But that didn’t stop me feeling like a lovesick teenager at the first sight of Willie. And there’s another reason that first love is so powerful; I don’t think women ever tire of feeling like teenagers. We love the frisson and the excitement of those feelings, the near hysteria and the intensity. However happy a marriage is, we don’t often experience that sort of intensity, and this is one reason that people have affairs, because it makes you feel alive. Seeing Willie again took me back to those teenage days, when feelings are so much more intense than they ever are again, partly because they are so immature and instinctive, and real life has yet to dilute your feelings.

I won’t ruin the story by telling you what happens to Marina and Tom, but personally I have finally come full circle. I was shocked by the powerful feelings Willie was still capable of engendering, so shocked that I wrote a book about them. Now I have done that, I am cured. I saw him at a recent literary festival and for the first time ever he left me utterly cold. It was nice to see him, in that it’s comforting to see someone from your dim and distant past. But there was no frisson, no excitement and certainly no butterflies. Which was a relief, if a tad less exciting.

The Ex-Factor by Helena Frith Powell, Gibson Square Books, £7.99. Available from The Times Bookshop for £7.59 (free P&P); 0845 2712134, thetimes.co.uk/bookshop