Science is finding that women struggle more than men when it comes to staying faithful in relationships.

“Even when your marriage is good, you still miss that rush of feeling so excited you can’t eat or sleep when you’re having such an intense time emotionally and sexually with a new person. That’s what I kept going after, and what I couldn’t say no to.”

That’s how Annika*, 45, from Melbourne, describes her experiences with cheating, and she’s far from alone. According to a growing body of research, many women in long-term relationships are sexually adventurous and have secret lovers.

The view that it’s mostly men who cheat because their partners lose interest in sex is outdated. Science says that it’s actually women who struggle more with monogamy because they get bored in the bedroom. Women crave sexual variety and while some stifle their desire, others will be unfaithful.

Wednesday Martin, an anthropologist and author of “Untrue,” refers to this new research as “the great correction.” Martin interviewed dozens of sociologists, sex researchers and anthropologists for her book on female infidelity and says the sad, sorry picture painted of the female libido is grossly wrong. It is alive and kicking — and eager to be satisfied.

“The new research is correcting false notions that women have lesser libidos, that women are more naturally monogamous and that it’s easier for women to partner for life,” explains Martin. “Women don’t like sex less [than men] — but they do get bored of sexual sameness.”

While males may have higher levels of spontaneous desire, women take the lead for responsive or triggered desire.

“Spontaneous desire is when you suddenly think, ‘It would be nice to have sex.’ It comes over you like hunger or thirst,” says Martin. “Responsive or triggered desire occurs when something suggests the idea of sex to you — you’re watching or reading something, or a partner initiates a sexual encounter — and you get turned on. For that type of desire, women’s libidos are every bit as strong as men’s. We’ve internalized this idea that men are the randier sex and that’s untrue.”

The reasons women cheat

Martin says the myth that women cheat for emotional reasons while men cheat for sexual reasons is also being overturned. She cites research by Missouri State University on a group of women who used the Ashley Madison website specifically to cheat.

“[This research] explodes several of our most dearly held notions about female infidelity: that women cheat only when they are unhappy in their marriages; that unlike men, they seek emotional connection, not sexual gratification; and that women just ‘stumble’ into affairs,” says Martin.

“The women studied went on the site, created a profile, vetted candidates, met them in person and ‘auditioned’ them. This was a very intentional process. They wanted to find partners for sex. They reported being in sexless or orgasm-less marriages and they simply wanted what they couldn’t get at home. But most were otherwise happily partnered or married, and these affairs were a way for them to remain in their primary relationships. So, there goes the myth that women who cheat are unhappily married.”

Another critical piece of research from Dr. Marta Meana at the University of Nevada found that “institutionalization” in a long-term partnership dampens women’s sexual desire more than men’s. Men who have regular sex with their partners are more satisfied sexually and with their relationship, but it’s not the same for the women, she says.

“Now sex researchers are entertaining the possibility that women simply need variety and novelty of sexual experience more than men do,” Martin says.

It’s a notion women like Gabriella*, 28, from Sydney, have been aware of for some time. “I’ve had lots of affairs since my first long-term relationship when I was at university,” Gabriella says. “I love sex and I get bored easily, but men take [an affair] as an affront to their masculinity. They all think they should be ‘enough’ for me and when I try and discuss ways of keeping the interest alive, they treat me as if I’m not ‘normal.’ What should ‘normal’ be — a woman who lies back and puts up with boring sex just for the sake of it? That’s the story women have been sold and it’s just wrong.”

Further exploding the myth that women are made for monogamy is the work of biopsychologist Meredith Chivers at Queen’s University, Canada. Chivers and her team invited men and women to watch porn while they had monitors on their bodies to measure their physical response and blood flow, which showed their sexual arousal. Straight men were mostly turned on by images of heterosexual sex and women having sex with women, but the heterosexual women had a more varied “arousal menu.”

“Women’s bodies responded to men having sex with men, women having sex with women, men and women having sex and images of an erection. We traditionally think men get turned on by everything and the truth is that a woman’s body responds to more sexual stimuli,” says Martin.

Looking after lust and libido

So, does the unleashed female libido always lead to infidelity? It doesn’t have to, says Martin. Not if women can talk frankly to their partner about their desire for sexual variety and adventure. She says this can avoid the inevitable boredom that besets many long-term relationships.

“Women start providing service sex. ‘He wants it, I really don’t but I will get it over with.’ Then women get into the cycle of thinking, ‘I guess I don’t really like sex.’ It’s actually that they’re not liking sex with the partner they’ve been with for many years,” she explains.

A simple thing couples can do is start a new, exciting activity together, such as learning how to kayak or dance together. “Couples get a rush of the neurochemicals and hormones similar to when we experience puppy love. So, you can get that feeling of excitement without going outside your relationship,” she explains.

“Imagine how much better relationships would be if couples understood that when a woman starts to feel sexually bored, this didn’t have to mean the end. Think of the marriages and relationships that could be improved if women could discuss their desire for sexual adventure and work with their partner to find solutions that bring them closer together.”