Here's why I left my wife for my mistress (and what my ex could have done to make me stay)

About 12 years ago, I came home with a new Labrador puppy. My wife, Maggie – mother to our primary school-aged ­daughter – looks shocked. 'I thought you were joking about feeling lonely,' she says.

No, I wasn't joking. And no, Maggie and I still weren't talking in the ­evenings, we continued to feel more distant by the day, but at least I had the distraction of cleaning up Scotty's dog poo.

This giant furball even slept on top of me in bed, which distracted me further from our marital problems.

But having Scotty to look after means that – for a short time – I don't feel ­useless or lonely. Scotty would reach the grand age of seven before I felt any genuine ­happiness again. That was the summer I met Caroline, the woman with whom I began an affair, and whose story you read in these pages last week.

I do not hate my (just) ex-wife. ­Maggie isn't unkind, or a nag. She was and remains attractive. We raised our daughter with loving kindness. So why did I do this terrible thing?

By the time I chose to ask Maggie for a divorce, our 20-year-marriage had been dying the way Hemingway said we go bankrupt: slowly, then suddenly.

I met Maggie in the first term of ­university – she was studying law and I was doing a degree in English. We were both shy and rather bookish. I worked up the courage to ask her out by first asking out two of her friends on embarrassing first dates.

Maggie is very bright, with excellent taste in art and a soft spot for heavy metal that I still don't understand, but that charmed me all the more.

After five years of dating, we ­settled into a functional and mostly loving marriage. Maggie became a commercial ­lawyer and I followed my dream to be a writer. We bought a small house in an up-and-coming neighbourhood of Edinburgh. Before long, we had a daughter.

I enjoyed fatherhood so much that I was happy to dial back my career in the performing arts to be the stay-at-home parent, as I made significantly less money than Maggie. I truly didn't mind. To start with, I loved where we lived and how we lived.

It's said that frogs, if boiled quickly, will jump out of the pan. But if you raise the temperature slowly, a degree at a time, your frog will be boiled with few complaints. Our frog started sweating when we had our daughter.

What people don't tell you is that you'll be in competition with your children and your children should win. Kids are objectively ­wonderful, and you should cherish every moment with the selfish, snuggly monsters, but they are also the enemy to marital love.

For years, our daughter insisted on coming into our bed every night. I felt she should return to her own room but ­Maggie was happy for her to stay. This started to get in the way of our intimacy. I don't just mean the sex, which I have learned to live without at times of my life. What I started to miss most as a man was conversation.

One night, when we went to bed, I turned to talk about our day. Maggie said: 'You're really chatty at night, you know that?'

I did know that. I thought Maggie knew that. We were together for five years before we got married. But that night, she made it clear that she didn't like night chat as a policy.

There's nothing wrong with that; we were different people with different needs. I wanted conversation at night, she wanted to sleep. Maggie had a difficult job. I respected the choice. So, I stopped trying to initiate social intercourse.

By this point, it had become uncomfortable to smile before bed because she was tired enough to fear that the smile would lead to sex or, God ­forbid, a conversation.

Thirty years earlier my mother, in the middle of a argument with my father, confided in me that 'the bed is a battleground', and I had literally no idea what she was talking about.

To a teenage boy that sounded pretty cool, a battleground!

In our marital bed, Maggie began to adopt a defensive position, scrunched in the corner, knees and elbows ­strategically placed like razor wire to slow any invading force. And if that failed and I tried to go over the top, Maggie could always utter an angry sigh and I would retreat out of no man's land back to neutral territory.

When my daughter starts school, I feel lonelier than ever. She has new friends, so I feel I should get a few more, as well. I start going to therapy, exercising like mad at the gym and throwing myself into cooking: Jamie Oliver and Nigella Lawson seem happy enough.

Maggie agrees to go to therapy ­herself, but soon drops the process, finding it frustrating and unhelpful.

Eventually, I suggest getting a dog, to which Maggie absent-mindedly says 'OK'. So I am able to distract myself for a few years with a new, hairier and even more intrusive guest on our bed.

It's all companionable enough, if a bit chaotic for a while. But Scotty's arrival confirms a ­serious intimacy problem in our marriage.

I distract myself with my city. When our daughter was small, we lived in a very social part of Edinburgh, with theatre, film, dance, museums.

Later, however, we move to a more sparsely populated suburb, and a much larger house, a seemingly small trade to live far from my old friends.

Then disaster strikes. March 2020, Covid – and everything closes down. Living in a new area with no friends, I am stuck in a house with a teen who needs me less and less each day, and a wife who seems (to me) to prefer the solitary life.

In this larger house, Maggie could avoid me to her heart's content. I believe she was happy knowing I was there, but wasn't actually happy spending time with me. She likes the idea of me, but the fact of me is ­hairier, noisier, and needier.

A few months before the pandemic started, I meet Caroline on Facebook. Well, we didn't actually meet in ­person for at least six months, we just start chatting.

I wasn't looking for an affair; I had made many online friendships with men and women over the years. I'd had one brief infidelity with someone I worked with 15 years prior and I don't recommend the ­endeavour. Affairs are tiring and tiresome work.

But Caroline and I became fast friends, months before I saw her face and weeks before I heard her voice.

She, herself, had gone through a bad divorce a couple years previously and she makes it clear she has no interest in breaking up a marriage or getting involved. But again: we can't stop talking to each other. And while the talk is occasionally flirtatious, we usually keep to topics of ­general interest: the lockdown, the silliness of thinking that a mask worn over a chin could stop viruses.

I talk about my struggling sour-dough, my new kale and spelt recipe (my God, I'm so middle class) the terrible novel I am working on, my neurotic but lovable dog.

Any normal human would find the conversations pedestrian, but for two people starved of attention, they are golden moments.

Each time I talk to Caroline I feel better. I stop feeling lonely. I feel listened to. When we have embarrassing opinions, like, a love for the more politically incorrect humour in Carry On films, we share in both guilt and laughter.

Five years on, we still chat away like children at a slumber party. Of course, we do; she knew me long before she met me.

Six months after Caroline and I start chatting, I travel to London to meet her. I find myself very confused. I was hoping we could stay friends, or maybe have a short dalliance and that would be that. I'd scratch some midlife itch and it would all be over.

Caroline confides to me weeks later that she promised herself she wouldn't sleep with me. I told myself 'whatever we do, don't screw up this friendship'.

Of course we end up in bed within two hours of my arrival. It seems we can't stop doing that, either. That evening over an Italian meal, I realise I can't live without her. In fact, I can't imagine it.

How could I leave my wife of so many years? I don't at first. I do something both horrible and kind: I lie to everyone closest to me. How could I lie? Because I don't know if this is some sort of midlife crisis.

My work life utterly falls apart; the pandemic destroys my ­particular industry. I am doing some teaching, but however useful Zoom is, it's not a replacement for real social interaction.

The lost salary isn't an issue – but I am still alone in a big house and feeling more useless by the day. If there's one thing a man hates feeling, it's useless.

Then my mother dies, my father having died several years before. Something changes inside me – I realise we're not on the planet for very long. I look at my dog. I have been unhappy as long as Scotty has been alive, could I live another 40 years like this?

Is all this the claustrophobia of the pandemic, or just the routine bad judgment of middle-class, middle-aged men?

As the pandemic ends, I finally get a chance to see my therapist in person. I ask her if I'm really ready to leave my marriage, or if this is just some midlife crisis?

She says something I'll never forget: 'What some people call a midlife crisis is a natural part of realising your own mortality. You're going to die sooner than you'd like and you might want some happiness before you do. Maybe you're afraid of dying.'

She is wrong on that score.

I'm not afraid of dying. I'm afraid of not having lived. I choose ­happiness. I discuss with my therapist how to exit a marriage with as little pain as possible.

Unfortunately, my happiness would be bought with a lot of tears from me and my family, tears I would rather have avoided. But I never question my decision from that point.

I accept a job in Manchester that would start in the autumn of 2022 and plan how to tell my wife that our marriage is over.

The next week is a nightmare. I say to my wife that I wish to end the marriage. And I want to die as I watch her heart break.

My advice for someone who wants a divorce is: avoid it if you can.

I don't tell her about Caroline at first, because the problems in the marriage have nothing to do with her. But I am also scared and ashamed. We plan to tell our daughter in a week, but the tears keep coming and we are miserable and my daughter can tell. So we tell her together, I watch her heart break – and I die all over again.

Later, my wife begs me to ­reconsider. She claims she knew nothing about my loneliness, despite me reminding her of every time I told her 'I'm lonely'.

I remind her of why we got Scotty. And that makes her feel blamed, so I back off.

I try to tell her that I need things I don't think she can give. And that this doesn't make her a worse person – maybe it makes me too needy. We sleep in the same bed for another day or two, and we hug each other, crying in the night, but we don't go ­further than that, because it is over.

But, back in my new place, I feel like a weight has been lifted from my chest. I bike around Manchester feeling happier than I've felt in years. I feel free and invincible.

Maggie is not – and has not been – the bad guy. I was with her for 20 years and I wasn't wrong to be. She is a good person who remains a friend.

When I'm in her area and go back to see our daughter, I stay at our old house. I help with Scotty and take him to the vet when he develops a tumour. With treatment, we are able to extend his life for another two years.

Maggie soon puts the timing together and guesses. Thinking back, she realises that all during the pandemic when she's ­avoiding me, I'm in another room talking to Caroline.

She feels hurt and guilty, ­realising she left me alone for so long, and she feels stupid for not noticing I was cheating on her under her nose.

Yes, I still feel ­terrible about lying to her. She feels I never gave her a chance to fight for me. Instead of reminding her of all the times I told her I was unhappy, I apologise.

My daughter is angry with me for a time but, when she meets Caroline, much of that anger melts away. She sees how nice she is and how happy ­Caroline makes me.

The divorce process itself is amicable and we settle on a reasonable split to keep us and our daughter ­comfortable.

Our marriage, and our dog, die within months of each other. Again, I am reminded by tragic circumstance that life is short. And if life is so short, I believe you should spend it with people who want to spend it with you.

Love is just that – you really like the person in your bed and vice versa. And you want to know what's going on in their lives and in their heads; you're dying to know what happens next in their life. Because you are. Dying.

'I've never seen you look so happy,' my old friend says to me. I have just introduced her to ­Caroline. My friend is no fan of adultery but she sees the joy in my eyes and she has just met the woman I want to spend the rest of my life with and love more deeply than anyone I've ever known in my life.

I'm not saying that every ­middle-aged bloke who realises they're mortal should run out on the people they love. But for the sake of the few years you have alive, talk to the person in your bed, listen to them.

Make space for everyone in your life. Live while you can.

• Names and details have been changed. Nathan ­Hetbridge is a pseudonym.