This story originally appeared in June 2015
Janet Dee met her husband when they were both in their 20s - she, armed with an accountancy degree and ready to start work in a multinational bank; he, with a degree in history of art and no idea what to do next.
"I was always the more ambitious," says Janet, now 48. "I did very well, very quickly." Married within three years, Janet was pregnant a year after that. "I was keen to keep working, and Paul was happy to stay at home and look after our daughter, so it seemed perfect for him to provide 'Daddy day care'."
The arrangement allowed Paul to pursue his "portfolio" career, spending hours online studying paintings coming up for auction, which he bought and sold, while Janet made her way to the top of the career ladder - where she now commands a six-figure salary and generous annual bonus - giving birth to a son and another daughter on the way. "I went back to work months after having each of them," she says. "Of course I missed them, but I was happy with the way Paul and I made things work; I thought he was, too."
Evidently not. Six years ago, Janet found some rather incriminating texts on Paul's mobile phone. When confronted, he confessed he'd been having an affair with a single mother he met at the school gates.
"She was vulnerable," says Janet. "I guess he liked that. It made him feel like a hero."
Her experience sadly chimes with the findings of a new study of more than 2,750 young married people by the University of Connecticut, which showed that men who are financially dependent on their spouses are the most likely to be unfaithful. In fact, the bigger the earning gap, the more likely they are to have an affair, with those who rely solely on their wives for their income the biggest cheats. In contrast, bread-winning women in such marriages are least likely to stray.
"Infidelity may be a way of re-establishing threatened masculinity," suggested lead researcher, Prof Christin Munsch. "Simultaneously, infidelity allows threatened men to distance themselves from, and perhaps punish, their higher-earning spouses."
Janet certainly feels her punishment was unduly harsh. Although Paul broke their marriage contract, as he was also the main caregiver and she was seen as the breadwinner who was rarely at home, she lost everything.
"He took the house, half my pension, half my salary - and, what's worse, the children," she says.
She now lives in a two-bedroom rental property in the "wrong" side of her town while Paul has the former family home for her three children - plus his girlfriend and her brood.
"I live no more than 10 minutes away, but emotionally, we're a million miles apart," says Janet. "My eldest is 12 and she barely comes to see me any more. I don't feel like a proper mum."
The househusband may be a relatively recent phenomenon, but with 31 per cent of British women now the main financial provider in their family - up 80 per cent in the past 15 years, with an increase across all age and income groups - and 75 per cent of next year's graduates female, it's one only set to rise. And it's one men claim to be comfortable with: figures in February from Match.com, the dating website, suggested that 87 per cent would be happy to marry a career-driven woman - what has been dubbed the "Clooney effect" - even one who earns more money than they do.
Which leaves women in an apparent double bind. One minute we are wearing the trousers. The next, as Davina McCall is busy telling us, we need to be wearing matching undies (and a pair of marigolds) if we don't want them to stray.
"The problem is one of social stigma and whether men feel validated or not," says Andrew G Marshall, marital therapist and author of How Can I Ever Trust You Again?
"Men are brought up to be providers. Very few men stay at home and look after the children because that is exactly what they want to do. It usually comes on the back of a bankruptcy or ties in with losing a job.
"Part of the problem is that a stay-at-home husband ends up in a whole new circle, most of whom are women. This can make them feel very alienated."
But the idea of the put-upon house husband is not one bought by Dr Helen Fisher, human behaviour researcher and author of Why Him? Why Her?
"The type of man who chooses to stay at home is biologically wired to have an affair," she says.
"He will, most likely, be an entrepreneurial type who registers high on the dopamine scale. Dopamine is associated with spontaneity, unpredictable behaviour and addiction. Give this type of man time on their hands and ... you get a man who strays."
Of course, it certainly doesn't have to be a disaster. My (now former) partner put his career on a partial hold so I could pursue mine, while our two eldest children were small. He got a certain form of social kudos from being a househusband. Every woman I knew was deeply impressed and rather envious. He got a lot of praise, much more than stay-at-home mothers get. The upshot of this time at home is that, now, he is still very domesticated, a far better cook than me and he has a very close relationship with his children, even though we split more than three years ago.
Kate Jarvis, like Janet, was not so fortunate. Founder of a successful home catering company, with a small factory unit and a staff of 20, her husband was "let go" from his job as a sound engineer when their first child was born, so it made more sense for her to plough on while he picked up the slack at home. She believed (because he told her) that he was proud of her. Then, two years ago, she found out he was having an affair with a woman who had a stall at the local farmer's market - where Kate had started out many years ago.
Although they sold the family home and both downsized, her ex now has custody of their two boys, aged 13 and 11, who she sees every other weekend and for her portion of school holidays.
"I thought I was doing the best thing for everyone. I didn't expect this," says Kate. "I wanted my children to know how hard I worked, but I was there every night, every weekend. I had a passion about work that my then-husband never had. I love my business and I am proud of what I have achieved, but look at what I have sacrificed."
The counter-argument is that this has been happening to men since time began.
"We are not used to stories of women losing custody of their children," agrees Marshall. "Few would expect to do so because they were pursuing a successful career. It's a new phenomenon that seems punitive in the eyes of many women."
For him, the key to handling this unexpected flipside of equality is communication and negotiation.
"Most men don't have affairs," says Marshall.
"But they stray when they are desperate, when they feel unheard, un-listened to. It is demeaning to say they need their ego stroked, but when you step off the primrose path - and by this I mean the usual path most go down - you need to do a lot of talking.
"If a man feels emasculated and as if he has lost his purpose in his life, he needs to ask himself some hard and difficult questions: 'Who am I? What gives my life meaning?' The easy question is: 'Do I fancy this other woman?' The simple answer to that is often 'yes'."
For Janet and Kate, all these questions come too late. They both still feel conflicted about what has happened. "I don't know who to blame," says Kate.
"Neither of us ... both of us ... all I know is, I have been punished for being a successful woman in a way I never expected."
• Some names have been changed