I haven’t kept many things from my teenage years. I have a box of photos – hazy snapshots from holidays and parties, captured on disposable cameras and developed at Boots. I have a stack of A-level psychology notes, kept in homage to my subsequent career. And I  have a letter, from a boy called Ben (not his real name), written when we were both 17. We were friends first, and then he was my boyfriend, and then he broke my heart.

I took the train to school, and for years Ben and I would walk to and from the station, sometimes bouncing a tennis ball back and forth between us as we spoke. We discovered films together, and music and books, and at the weekends we got drunk with our friends. When half of our year group descended on Newquay for a week after our GCSEs, we lay on the beach together one night, singing at the top of our lungs. More than anything, though, we talked: about life, about who we thought we might be, and what we wanted from the blurry future ahead.

In the early years, Ben and I were “just friends”: I had a boyfriend, then he had a girlfriend. But eventually, inevitably, something happened. We were 17, and in the stretched time warp of the teenage years, it truly felt like we had waited for that moment for ever. I had driven to his house after a party, his parents were out, and on the sofa in his living room, we kissed. I remember we said “Oh my God” to each other afterwards, again and again, all the words blending into one. It wasn’t even days before I told him I loved him; it was barely an hour.

The weeks that followed were weightless. I was delighted to be seen with him, for people to know I was his girlfriend. Around that time, he wrote me the letter. It began with the list of things he loved about me. Then he told me he couldn’t believe this was happening, that whatever difficulty we had now or in the future, we would work through it, that he couldn’t believe how lucky he was. He ended with the words: “Sorry for the incoherence of this letter, I want you in my bed.” If I had been on cloud nine before, that letter sent me into space.

About two weeks later, Ben broke up with me. There was no clear justification – maybe something about wanting his freedom, but nothing that remotely explained how abruptly and totally he had changed his mind. But that was it. I had to go to school with him the next day, and every other day after that. Due to a stroke of adminsitrative bad luck, we sat our A-levels at adjacent desks. Then, and every day since we had broken up, he blanked me.

The immediate aftermath was awful. I remember standing in the shower, wondering how long it would take me to stop loving him. Of course, I did stop eventually: I went to university, moved on with my life, and fell in love again. But for years, I would dream about him regularly. The dreams were always the same: we were reunited in some way, and he apologised. Often, my now-partner appeared in the dreams, maybe an attempt from my sleep-addled brain to remind me that things had long moved on, that I was happy now. Until recently, I was truly ashamed of these night-time visits: a woman in her 30s still dreaming about a brief teenage love affair.

Then I started writing a book about adolescence. In doing so, I realised I wasn’t the only one to experience a hugely impactful relationship in my teenage years. I read about a 2003 study, in which adults aged 20 to 94 were asked to recall when in their life they had felt various emotions most strongly. Participants in their 20s tended to report being most in love right now, but for all other age groups, the peak was at age 15. When I read about this it floored me: these are often the most emotionally intense relationships of our lives.

Yet in society, teenage love is dismissed. The phrase “puppy love” is used, denoting something juvenile: a transient, infantile affection. There seems to be a real appetite and respect for teenage lovers in fiction – from Romeo and Juliet to Normal People’s Connell and Marianne – that is utterly at odds with the attitudes held about teenage love in the real world. It is as though we give ourselves permission to acknowledge the power of adolescent love in stories, but cannot acknowledge it publicly about ourselves.

This dismissal has huge consequences for actual teenagers, from the simple fact of their pain being ignored to something far worse. In 2023, 15-year-old Holly Newton was murdered by her 16-year-old ex-boyfriend, who had obsessively stalked and controlled her. Despite it being obviously relevant that they were once in a romantic relationship, the courts have not officially recorded that Holly was a victim of domestic violence, because she was under 16. But there is ample research evidence that teenagers, particularly boys, can be violent and abusive to their romantic partners, and that the psychological consequences for victims are just as real as they are in adulthood.

Once you understand the context of adolescent development, the gravity of these relationships becomes easier to understand. Adolescence is a critical period of identity formation, when for the first time we grapple with that fundamental question: “Who am I?” We look to others for the answer. The psychologist Erik Erikson, writing in 1968, summed up adolescent love as an “attempt to arrive at the definition of one’s identity by projecting one’s diffused self-image on another and seeing it thus reflected and gradually clarified”.

On top of this, in teenage relationships, developing identities become intertwined. When my own relationship ended at 17, I realised that everything I’d discovered about myself over the preceding years was knotted up with memories of Ben. The only way to extract him from my brain was to destroy pieces of myself, obliterating the nascent identity I thought I liked. Seeing it through this lens, I finally started to understand why the aftermath was so hard.

For the first time, I also began to understand things from Ben’s point of view. The research shows that teenagers often initiate break ups when they feel the relationship is hindering or blocking certain fundamental needs, such as for intimacy, autonomy or social status. To a teenager, a romantic relationship can represent a liberating opportunity – for sexual experience, personal affirmation, social status, fun – but if it then traps them into a commitment, it can quickly end up becoming precisely the opposite. I understood that the boy I had given my heart to was an adolescent too, just trying to understand who he was.

While I was writing about all this, something else happened: I saw Ben again. One of my friends from school had stayed in touch with him, and we were both invited to her wedding. On the day itself, as I got ready in my bedroom in the hotel, my nervousness made me numb. Somehow my legs carried me downstairs, and then there he was: right in front of me, talking to me with his wife by his side.

By seeing Ben as a married man in his 30s, I realised the 17-year-old who broke my heart didn’t exist any more. That boy had been replaced by a stranger who merely looked like him. Finally, the ghost that roamed my nocturnal mind began to fade. But I will always keep his letter. That letter represents a fundamental experience that made me who I am: truly loving someone for their mind, and being loved like that, however briefly, in return. It also represents the fact that I coped with being unloved, at a young and fragile age, and that’s part of who I am as well. The letter was a wound, and then a scar, and now I am finally healed.

• Lucy Foulkes is the author of Coming of Age (Vintage).

Further reading

Conversations on Love by Natasha Lunn (Viking, £10.99)

Inventing Ourselves by Sarah-Jayne Blakemore (Black Swan, £10.99)

The Incredible Teenage Brain by Bettina Hohnen, Jane Gilmour and Tara Murphy (Jessica Kingsley, £16.99)