New York (CNN) -- Could letting your man sleep with another woman help your relationship?

Author and former mistress Holly Hill thinks so.

"One of the main things that I have learned is that a woman that negotiates infidelity with her partner is far more powerful than a woman who is sitting home wondering why he's late from the office Christmas party," she says.

"It's better to walk the dog on a leash than let it escape through an unseen hole in the back fence."

Hill's memoir, "Sugarbabe" details her yearlong adventure with a series of so-called "sugar daddies." The book sold 24,000 copies in her native Australia, according to her publisher, and has just been released in the United States. Holly Hill is a pen name.

"I thought it was men that would like the book," she says, "But in fact it's women, because what it says to women is that if your man cheats on you, he still loves you, and he's probably running about average."

Allowing their men to stray is a concept that's difficult for most women to contemplate.

But Hill says that if a woman takes the time to truly examine her relationship and considers Mother Nature's unerring spell on men's libidos, she might realize that letting her boyfriend or spouse know she's OK with him having sex elsewhere is a logical way to prevent him from doing it in secret.

"I think that cheating men are normal," says Hill. "Monogamous men are heroes. Monogamy does have a place in relationships, but not on the long-term. Men are hard-wired to betray women on the long-term."

But psychology professor Lawrence Josephs believes it is more personality type than gender that indicates whether a person might cheat.

"People who are higher in narcissim -- whether they are male or female -- are more likely to cheat. People who feel entitled to it, people who have what's called avoidant attachment style where they tend to have more impersonal sex," are more prone to straying, he said.

The professor also said people who experience lower levels of empathy or guilt tend to engage in more infidelity.

Hill says, that of course it's every woman's right to refuse to have sex when she's not in the mood or has a headache. However, expecting men to cope on their own with no outlet whatsoever is shortsighted and cruel, says Hill.

The author, who holds a psychology degree from the University of Southern Queensland, says her experience as a "sugarbabe" taught her some valuable lessons about what drives men to seek sex outside marriage.

Finding herself in financial dire straits after her married boyfriend unexpectedly dumped her four years ago (he had persuaded her to quit her job and enjoy his financial support as part of "the mistress plan"), she decided to get creative about her employment options.

Hill, who was 39 at the time, posted an ad online announcing her search for a sugar daddy, someone who would pay her $1,000 a week in exchange for her company, cooking, conversation, massages and, when they desired it, sex. She says the ad attracted 11,000 responses.

At the time, Hill says she saw a distinct difference between what she was doing and prostitution.

"I thought that because I was a 24/7 exclusive mistress that I wasn't part of the world's oldest profession, but with hindsight I was, because what I was doing ... I was charging men for services, part of which included sex," says Hill.

However, she adds, any married woman who no longer loves her husband but continues to have sex with him to retain the comforts of being married could also be considered part of that oldest profession.

Most of Hill's "daddies" were wealthy married men who surprisingly often opted for conversation, she says. While entertaining with red wine and exotic food platters she'd prepare in her Sydney apartment, Hill learned that most of these men sought her attention because they simply weren't getting enough sex from their wives.

"Men need to get their rocks off," says Hill. "If a woman crosses her legs for any length of time and doesn't arrange some sort of alternative for her man, he is going to cheat on her."

By alternatives, Hill is referring to her idea of "negotiated infidelity." That shouldn't be confused with an open relationship, which to Hill "has no rules." Nor does it imply that it's necessary that a wife allow her husband to hop into bed with whomever he chooses -- unless of course she's OK with that. Hill says negotiated infidelity could mean hubby makes a trip to the local strip club for the occasional lap dance or updates his porn collection.

And in no way does it have to be a one-way street.

"Ideally the woman will want to stray as well," says Hill. "Some won't want to because they're at home taking care of toddlers. But the woman definitely needs to negotiate infidelity as well, especially because that will generate her man's competitive nature. The more lovers the woman has, the more attraction the man will have for his partner."

But how do women -- and men for that matter -- get past those ingrained feelings of possessiveness and jealousy?

"Women need to remember the difference between why women and men have sex," she says. "Women tend to value intimacy. For men it's often the thrill of the chase, or the quick sex with a stranger. Men don't even have to know their lovers' names! It's often just a cheap thrill and has nothing to do with us as a loving girlfriend or wife. Once we understand that, it's much easier to let him go off."

But Josephs doesn't think understanding will overcome jealousy.

"I think what's universal is that no one likes sharing partners -- whether you're male or female. I think jealousy is a kind of universal emotion," the professor said.

Her sugarbabe days now over, Hill lets her boyfriend of two years, Phil Dean "go off" on occasion. Hill says she believes negotiating their infidelity has been instrumental in keeping their relationship strong and committed, not to mention electric.

"[Dean] can have sex with the Australian women's basketball team for all I care, but he can't spoon any of them," says Hill. "For me, spooning is cheating."

Dean, 45, who works for an insurance company in Sydney, jokes that he hasn't slept with any members of the Australian basketball team. But he is a big supporter of negotiated infidelity.

"I was actually very relieved when Holly and I started to speak about it [at the beginning of the relationship]," he says. "She asked me if I'd be happy in a monogamous long-term relationship and I had to say 'no'."

And while Dean says he doesn't get jealous when Holly spends time with another lover, some of his male friends are certainly jealous of his relationship's flexibility.

"Some think it couldn't get any better than what I have," says Dean. "Some, however, don't want to embrace the concept. They feel protective of their partner and don't want to share."

Central to the idea of negotiated infidelity, Hill says, is each couple figuring out what their boundaries are. While she admits she shed a few tears at the start of her relationship as she and Dean tested their comfort levels with different arrangements (Dean also says it has definitely been a learning process), they're now very clear about what they will and won't allow.

While Dean has the green light to have sex with other women, he's not permitted to stay overnight. He also can't take his lovers away for romantic weekends. And Hill says she'll have an all-out hissy fit if he spoons another woman.

Hill, on the other hand, is allowed to spoon her lovers because Dean has no problem with that and recognizes that intimacy is an important part of sex for women. Hill isn't, however, allowed to wear any of the outfits Dean has bought for her when she meets up with a lover.

But how can Hill be sure Dean isn't spooning if she isn't there?

"If you're talking about sexual needs honestly with your partner, you get better at communicating with each other, you get better with honesty," says Hill. "Everything is out in the open and you have an honest relationship according to your man's biology, not according to some outdated social norms." (Hill is working on another book that will address why women also like to venture outside their marriages for sex.)

Those rules sound artificial to Marcella Weiner, adjunct professor of Marymount Manhattan College and author of "Repairing Your Marriage After His Affair: A Woman's Guide to Hope and Healing."

"Unless you're totally dead inside of you and have no heart or no brains or no anything -- when you're with another person, you're with another person," said Weiner. "It's not just here's my penis, here's your vagina that's it. It is for some people -- but that's a mechanical kind of thing."

While it may not be for everyone, Hill is optimistic that if more people embraced the idea of negotiated infidelity, cheating could become a thing of the past, leading to fewer divorces and truly happy lifelong relationships.

"We just have to be honest about the way nature created us, and we have to work with nature instead of working against her. This isn't rocket science. This is what every man already knows and I think what every woman deep down already knows."