I’m in my 50s and at least four of my friends are cheating on their husbands. And no, it’s not about sex…

‘He doesn’t suspect a thing,’ my friend Marylyn told me gleefully, as we sat in the restaurant over tapas.

Patatas bravas wasn’t the only spicy dish she was sharing. As the rioja flowed, so did the gossip surrounding her eight-month affair with a man called Phil – including all the ways in which she was hoodwinking her husband Sam.

‘I just tell him I’m off to the gym, and when I get back, I have a shower. He stopped asking me questions about my day a long time ago.’

‘But you must have to change into your gym clothes? Or he’d know you weren’t actually exercising,’ I said. ‘Yeah, I keep a pair of trackie bottoms in the car and I slip them over whatever I’m wearing. He rarely looks up when I come in – he’s usually scrolling on his phone.’

I didn’t feel bad for Sam. He’s always struck me as a grumpy, difficult sort of man. Marylyn often talked about his erratic moods and the way he criticised her appearance.

No, Sam wasn’t worth my faux concern. The question is, why was I the friend Marylyn turned to when she wanted a sympathetic take?

For that appears increasingly to be my role in life: the pal to whom people confess their marital infidelities.

Yes, I’m a good listener and a sociable person who is always at parties and events so am often ‘there’ for people to confide in, but ironically I think it’s because they think my own marriage is watertight. Since I have no personal experience of sexual betrayal, all I can do is nod and grimace and giggle in the appropriate places without ever demanding that they provide a willing ear in return.

There’s Marylyn and Becky and Laura and Rachel, and those are just the friends with existing, ongoing affairs. Another small handful have been involved with Other Men in the past but aren’t right now – I know this because I’ve sat through every twist and turn of their tearful fizzling out.

Yes, I am always deeply empathetic in person.

But inside I’m also quietly assessing and analysing these women who have got themselves into such messy situations.

I don’t judge but I do (internally) roll my eyes. Occasionally, I wonder if I’d still be their favourite confidante if they knew how much I roll them.

Marylyn, for example, is a 53-year-old events manager in the hospitality industry and nothing about her affair with Phil sounds like fun. The sex isn’t mind-blowing and the logistical admin required to keep it all secret feels like pointless hard work. Sometimes I suspect she is having an affair because the kids aren’t around much any more and she needs something, anything, to organise.

Can you imagine if Sam discovered her current To Do List?

Sam’s one saving grace is that he is not a ‘beige’ husband. If he were a colour, he’d be puce red. But many of the other women tell me they’re having affairs to escape their boring home lives.

Their husbands don’t want to do anything except come home from work and watch sport on TV. Dragged out to parties, they talk among themselves about their new EVs and their pension pots. Some of them go down rabbit holes online and emerge with ever-dafter ideas about drinking raw milk or green vegetables being bad for you. They never plan holidays or day trips, and rely on their wives to do all the social organising.

I don’t blame my friends for wanting to escape this, though I do blame them for their lack of honesty to themselves.

They’ve checked out of their marriages but aren’t brave enough to end them completely. The house, the joint account, his fat pension, the kids. Life is short but still too much is apparently at stake for them to go it alone.

I sit through endless dissections of the sex too, though sometimes I tune it all out. Becky was only sleeping with her husband Pete on anniversaries and birthdays, and even then it was ‘the most vanilla sex you can possibly imagine’. Rachel hadn’t had sex with her husband for two years. Naturally their new lovers were far more enthusiastic and proficient.

I wondered if these men had wives at home who were also bored in bed. Is novelty all we’re looking for?

Becky’s chap David was ‘trying out every position in the Karma Sutra, like he might run out of time’, she giggled. She met him at a Bikram yoga class in Chiswick, west London, and they got talking afterwards.

‘I suspect I’m not the first woman he’s had an affair with,’ she told me. ‘He’s in his early 40s and very good looking, but I don’t care if he’s seeing other women. It’s just fun.’ And yet I know she’ll call me in a few weeks or months’ time to share a bottle of wine and pour out her heart because he’s dumped her.

Laura, 49, works in an art gallery in London’s Chelsea, and has been married for 17 years. She only communicates with her lover Dan on Instagram, then quickly deletes their message history.

She texts him more than she texts her two children, friends and husband Michael combined.

‘When we meet it’s like fireworks. It’s such an amazing connection,’ she tells me.

But is it? Why doesn’t she just leave beige Michael and start again as a single woman, I think to myself. She suspects Dan is playing the field a bit and doesn’t want to settle down. ‘I’m so attracted to his enthusiasm about everything. He’s a journalist and I’d never met a writer before. He’s always interested in everything I say, which is so different to Michael.’

Even so, they’ve only had sex a handful of times since meeting a year ago, usually in a local hotel.

‘It’s the messaging that feels most addictive,’ she told me. ‘Michael doesn’t talk to me about anything meaningful anymore and I don’t know the minutiae of his life like I know Dan’s.’

Sometimes she’s messaging Dan in the passenger seat while Michael drives her to work. ‘At first I set myself a rule not to text Dan when my husband was around. Then after six months I realised I enjoyed doing it with him there. It made things feel more exciting. Is that wrong?’

Well, yes.

‘I guess we’re trapped in a Mexican stand off,’ she once told me of her relationship with Michael. They have stopped communicating their feelings to each other and bicker more than talk.

But she doesn’t think he’d ever have the guts or the chutzpah to have an affair himself.

And yet I happen to know that he did, a few years back. Laura was going through a cancer scare at the time, and of course it wasn’t his finest hour. How do I know? Because the woman he was sleeping with was another friend of ours, and she told me.

None of it is very edifying and almost everyone, it seems to me, is lying to someone else. I admit the details are often juicy and some of the sexual techniques rather eye-opening.

But if my now-extensive knowledge of the midlife woman having an affair has taught me anything, it’s that they’re fooling themselves just as much as their husbands. They think they’re getting back in touch with their feelings when in fact they’re blocking them off.

If you’re unhappy or bored enough in your marriage to have an affair, the honest thing to do is see a divorce lawyer.

But I never say that to them. Sometimes friendships, too, are built on deceit.

Jennifer Haldon is a pseudonym. All names and identifying details have been changed.