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.