When I told my husband I was interviewing a writer who thinks men should give their wives a ‘cheat pass’ this Christmas, he understandably had some questions. “How would the wife find someone suitable for the occasion?” he wondered. (We were talking in the abstract, of course, and I deemed it safer to treat this as rhetorical.) I assured him that yes, it was all very unfeasible, and concluded he’ll more likely gift me jewellery.

But Wednesday Martin, whose latest book Untrue explores “why nearly everything we believe about women and lust and infidelity” is wrong, is not being flippant. “We now know long-term relationships are harder on female desire than they are on male desire,” she says. “Many experts now believe monogamy is a tighter fit for women than for men. This Christmas give your wife something she really wants. Something truly exciting. A hall pass.”

This, for the uninitiated, is an agreement between partners in a romantic relationship that one or both may sleep with other people. You’d have one if, say, you were into polyamory, which involves having “intimate relationships with more than one partner, with the consent of all partners involved.”

Confused yet? Or just wondering how all the logistics would work, never mind how on earth to broach the topic with your significant other? Martin, when we meet at a boutique hotel in South Kensington during her visit to London from the US, has plenty of answers. Starting from the premise that we’re only now beginning to understand women’s sexuality properly, she explains that contrary to popular opinion, women tire of their sexual partners faster than men, and need just as much sexual adventure and novelty as their male counterparts – if not more. To support this theory, she draws on a range of relatively recent scientific and social scientific studies, as well as interviews with experts on female infidelity in a range of fields and plenty of “untrue” women themselves.

Wednesday Martin: we‘re now seeing female sexuality is its own thing, not an extension of male desire credit: Heathcliff O'Malley/The Telegraph

“In one study [men’s desire] tapered off slowly over seven years, whereas female desire plunged in the first one to four years,” she says. “We might have said before ‘oh well, that’s because women like sex less than men do, but now the new data are helping us understand it’s not that women like sex less than men do, it’s that men are better at wanting what they already have and women struggle more with the same old familiar partner over and over.”

Martin, whose 2015 book Primates of Park Avenue: A Memoir became a New York Times bestseller, is not alone in her espousal of such ideas. This year has seen, if not an explosion, then at least a creeping insinuation into our culture of the idea that monogamy might not be the only approach to long-term relationships. Two of the most talked about BBC dramas of the autumn, Wanderlust and Killing Eve, had at their heart characters who rejected traditional relationships. In the former, a married couple who try out consensual non-monogamy to reignite their dull sex lives; in the latter, an attractive female assassin whose potent bisexuality and rotating cast of bed partners is almost incidental to the action. And that was just the BBC. Meanwhile we’ve had an MP, Labour’s Jess Phillips, recommending that schoolgirls should be taught about orgasms.

Martin believes the MeToo movement has also been behind the shifting sands. “Female sexuality used to be women being sexy for men,” she says. “That was how it was in Hollywood; that was how it was wherever men had power. It was very heteronormative and male-focused. Now, thanks to MeToo – and activists and journalists – we‘re seeing female sexuality is its own thing, not an extension of male desire.”

MeToo has given women a louder voice in the arena of sexual politics. And since female sexual autonomy is, argues Martin, a feminist issue, closely interlinked with the power and autonomy women have in the workforce and in politics, the significance of this online movement should not be overlooked.

In Wanderlust, a married couple bored of their sex life gave each other permission to sleep with other people credit: PA/Matt Squire/BBC

But Martin, a married mother-of-two and stepmother-of-two originally from Michigan, whose background is in anthropology, conceived of the idea for the book before MeToo became a hashtag. She struggled with monogamy herself in her 20s; more recently, she realised there were data indicating that she was not alone.

“What’s so exciting is there’s relatively new science and social science that flies in the face of the holy triumvirate of beliefs about male versus female sexuality: the first being that the male libido is stronger than the female libido; the second being that women are more naturally monogamous; and the third being that women are the enforcers of monogamy and are more cosy and domestic than men,” she says.

“All this exciting research had come out over the last years, picking apart every one of those supposed truths, but a lot of it hasn’t really crossed over. So I saw it as an opportunity to make the science and social science kind of relevant and fun.”

To this end, her chapter “Bonobos in Paradise” begins with a look at the work of primatologists regarding the sexual behaviour of female simians. We learn that “our primate sisters are sexual adventuresses, driven by the thrill of the unknown and unfamiliar. And not a few of them like to get busy with other females.”

A few pages later, Martin has segued into reportage from the front line of female sexual exploration: women-only sex parties, known as Skirt Club, and attended by women who identify as largely heterosexual, many of whom are married to men.

What she witnessed there didn’t only show female sexual fluidity in action in humans; it also busted another myth, she says – that women cheat for emotional connection.

“These women are going there to have one-off, more or less anonymous encounters with women,” she says. “There could be no more vivid illustration of the data about female sexuality than Skirt Club.”

Attending such an event won’t be everyone’s cup of tea. But, Martin believes, there is a universal lesson to be learnt. “I think people have to get creative if they want to stay with each other in the long term, and admit monogamy is hard,” she says. “I think when we admit that, it will provide such a wonderful relief to a lot of people.”

Jodie Comer played a bisexual, non-monogamous assassin in Killing Eve credit: Robert Viglasky/Sid Gentle Films

Admitting it is one thing; deciding what to do about it is quite another. And so we return to her idea of a hall pass. Is she really serious? And how would it even work?

“Ok,” she laughs. “So here’s the deal: consensual non-monogamy, I don’t think people in the mainstream know enough about it... but that suggestion stems from a YouGov study that shows one in five British adults said they had had an affair

“That’s an awful lot of people struggling with monogamy and believing their only option is to remain monogamous and unfulfilled or have an affair and pray it doesn’t blow up your marriage. What if,” she posits, “we looked at struggling with exclusivity after a number of years as simply the baseline, and gave people a whole range of solutions?”

She acknowledges consensual non-monogamy would not be the way forward for everyone. “[For] some people that would drive them absolutely insane and it would be a terrible idea,” she says. For those people, she suggests alternatives, such as trying to inject the spark back into the sex life you already have.

“The real gift would be to give your spouse permission to have the conversation,” she says. “Why is it better to get a divorce and move on when you simply decide ‘I don’t fancy him any more’, or the spark is gone... What a trail of destruction you might save yourself from creating if you said instead: is there something we can do here?”

Marriages, by this reasoning, could be saved. And something even bigger could occur: a societal shift in power relations between the sexes.

“If we have a pleasure revolution and start to put female sexual pleasure at the centre of our sexual universe, there’s a case to be made that that could change relationships outside the bedroom as well,” says Martin. “I hope so. We’ll have to see.”

Untrue : why nearly everything we believe about women and lust and infidelity is untrue by Wednesday Martin published by Scribe Publications RRP £14.99. Buy now for £12.99 at books.telegraph.co.uk or call 0844 871 1514