Can his mobile phone make him infertile? From that point on Jim worked hard in a stressful sales job and was a dutiful dad, taking the boys out every Sunday to give Cath a break and getting home each evening at 7pm to take over. According to stereotype, if men have a sexual problem, it's that they can't get enough, while women are the ones who invent headaches and feign sleep. In fact, this isn't true. A sex-therapy study by Relate found that, for half of the couples who attended counselling, the problem involved the man - most commonly lack of desire or erectile dysfunction.
Nina Bryant, a Relate psychosexual therapist with 18 years' experience, has found it increasingly common. Perhaps we are better at talking about it - the caring, sharing New Man feels more comfortable coming forward.
But there is also a feeling among professionals that we are expecting more of ourselves, and men, like women, are feeling the pressure. It could be that he's stressed, unhappy, tired or under pressure at work. Actually, it's about desire, expectation and emotion, and naturally that can ebb, flow and sometimes plummet.
The website Mumsnet - popular with mothers of young children - has numerous messages with titles such as 'Partner doesn't want sex any more' and 'Sexless marriage'. One desperate entry reads, 'I asked him if he wanted to fix the problem but he said he wasn't bothered, and that at 43 he has had more than his "share" of sex. This absolutely crucified me, especially as I'm not yet 30…' In another a mother appeals for advice. Yes, you read that right.
Women feel rejected and terrible. I kept asking if it was my body, but he'd never answer. He'd never been the sole breadwinner before; suddenly there were four of us to support. We were tired, there was no fun in our lives, it was just work, sleeping, feeding and babies.
Then Jim would try - though once he couldn't get an erection and that was heartbreaking. Whether it's been two weeks, two months or two years since you last did it, if it bothers you, the best start is to tell him,' she says. The more men worry, the harder it is for them to perform, and that anxiety can be quite insidious.
It's estimated that one in two men will suffer impotence at some point in their lives, and occasionally this can be a marker for diabetes or heart disease. It's also exacerbated by smoking and drinking. A number of straightforward tests can be carried out by a GP. In America, loss of libido in men is often attributed to the age-related drop in testosterone and treated with hormone supplements. Britain hasn't yet followed suit. Testosterone levels fluctuate, so it is hard to measure or prove a 'drop'.
In addition, some men enjoy an active sex life yet record low levels of the hormone, while others have higher levels but a lower sex drive. Here the advice, once you have a clean bill of health, is to talk. What really undermines a relationship is when you won't talk about it, so there's no understanding and you end up hating each other.
If not, sex therapy is designed to bring underlying issues into the open, help couples rediscover desire and get back into the habit of sex. For Cath it was Jim's refusal to communicate that ultimately destroyed their marriage. For years I was ratty and miserable. Their sex life suddenly picked up. He was upset, angry, stressed. While I was pregnant I tried to initiate sex once and he rejected me.
By then he'd done enough damage. I wasn't going to let him drag me down that low again. In contrast, Susan and Paul are a couple who've faced the same problem but stayed together. On the face of it they have a perfect partnership.
Married for six years with one son, they run their own business and spend their free time cycling, climbing, trekking and sailing. To all who know them they are affable, contented - almost, in the nicest possible way, the smug marrieds. However, they have sex only once or twice a year - and it bothers Susan. In my low moments I feel very tearful - that being sexual and desirable and desired is behind me already.
I'm 42 and I can't see anything changing. There's no sexual passion between us, but lots of love. I couldn't stand life without him. So I tell myself, "You can't have everything.