For many people, sex is is a numbers game.

The average number of sexual partners for women per lifetime is four. For men, it's seven.

The ideal number of both genders would like their partners to have had before them is 10.

And then of course, there's the number one.

One is the loneliest number when it comes to drinking and ping-pong, but for people who've only ever had sex with one person, it actually seems to be quite the opposite. For them, their sex lives are fulfilling, uncomplicated and totally not what you'd expect.

In fact, according to a study by two University of Denver professors for the National Marriage Project, people with only one notch on the bedpost tend to report happier marriages and greater relationship satisfaction than people with a more diverse sexual history.

Twenty-three percent of American couples fall under this category — a number we initially thought was stratospherically high until we realized that just a few decades ago, lifetime monogamy was the norm. Since the first infant breaths this country took back in the 1700s, it's been accepted — and encouraged — for people to go through life with just one sexual partner. The fact that the amount of people who've traded that up for a night of drunken debauchery or 65 has decreased by about 75 percent within such a short time is a testament to how unnatural the standards of monogamy can be for some people … yet for others, lifetime monogamy isn't unnatural at all. It's what feels right.

One of these people is Julia Hubbard. She thinks that her lifetime of sexual exclusivity with her husband Craig is responsible for the continuance of their 20-year-long marital bliss, something that's increasingly rare considering that divorce rates are hovering at about 50 percent these days.

"Lots of my married friends are in the process of splitting up and, of those still together, we are definitely among the happiest," she told the Daily Mail. "I like to think that, in part at least, it's because of my decision just to have sex with one man. I'm not wistful for any past loves, nor do I consider the grass might be greener with someone else."

Julia's one-guy-only decision was largely influenced by her parents, who raised her to believe that it was "morally right to wait until I was married to have sex."

However, much younger and much less morally unrighteous couples than Julia and Craig also live the happy lives of one-trick ponies.

Gabe and Monica, both 29, met through mutual friends when they were both just 15 years old. Although they'd fooled around with other peri-pubescents prior to meeting, they started dating and lost their virginities to each other all the way back in 2003. After that they just … never broke up. They weren't religious or of any sort of piety that would cause them to do this — they just really, really liked each other. Two years ago, they decided to marry, cementing themselves as the only people they'd ever, or would ever, sleep with.

"I've never felt like I was missing out on anything," Monica tells us when we ask her why she never went outside her relationship for sex. "What can I say? He's good in bed."

" Well … compared to what?" we ask, curious how someone who's only ever been with one person could tell good from bad.

"Good for me," she answers. "We're very communicative about each other's needs, and since we've been together for so long, we're aware we need to shake things up to keep it interesting. Sex is a super-important part of our relationship we put a lot of work into. If we didn't, it might not work as well as it does."

In that way, lifetime couples aren't so different from couples who've fucked and dated many other people — no matter what your relationship history is, you still have to put a shit ton of effort into certain areas for both people to feel satisfied. Yet … satisfaction doesn't necessarily equate to thinking each other are the only people out there.

When we asked Gabe and Monica whether they ever thought about being with other people, they both responded with a resounding "Of course." The difference is, they've just never done it. They don't feel compelled to.

"I've fantasized about thousands of other people," says Gabe. "That's not off-limits at all. I watch porn. We sometimes talk about finding other people attractive. There's zero part of me that feels like I have to be so monogamous … it just feels good for me to be. It's always felt right like this. I love her and I only want to be with her."

"… but that doesn't mean other girls aren't hot to him," Monica's quick to add. "I find other men attractive all the time! But attraction isn't necessarily what makes sex good. For me, it's the years of unconditional love and trust, and the knowledge that I'm with the right person."

This — this willingness to admit that they were attracted to other people — stands out. How are they able to feel so comfortable knowing the other is thinking about other people?

"There's a feeling of unquestioned loyalty when you've never been with someone else," says Gabe. "Neither of us have had the experience of being with other people … so that threat doesn't feel as apparent as it maybe would for a couple where both people have had a lot of other sexual experiences. It's almost like we exist in our own bubble … but because of that, we have to ground ourselves in reality. And the reality is that there are other people on this planet that are attractive. It just doesn't translate into action for us. Not even because of some rule we have against that … it's just that nothing compares to her."

Throughout the interview, the couple exuded a quiet confidence; the sort of steady, calm demeanor you rarely see in people whose ulterior motive is to fuck everything with a pulse. They explained this as a sort of pride in each other — they were both excited to hold the position of "only person you've ever fucked" for each other. Rather than see it as a limiting factor or a deficiency, they saw it as an honor.

Sobbing yet? Same.

Their relationship isn't without challenges, though. Both Monica and Gabe are constantly confronted by people who see their relationship as puritanical and strange. People assume they're religious zealots, and that they only have lights-out, missionary sex. People think Monica got pregnant early on. They assume she forced Gabe into some unholy marital slavery, or that Gabe "gave up" when he met her.

These assumptions, they say, used to be hurtful … until they realized people were just ignorant about relationships like theirs.

"I get it," says Monica. "We're in the minority. And the only examples you have in the media of couples like us are religious couples who get pregnant at age 16. It makes sense people would think that about us. But what's frustrating is that they tend to think we're so conservative that we won't even talk about this stuff, so we never get an opportunity to be heard. In reality, we're not conservative at all. We're actually pretty sexually adventurous and free-spirited in that realm … I wish people could expand their definition of happiness past their own."

"I wish people would give us more credit," says Gabe."If this wasn't working, Monica or I would have left way before this. Thing is, it is working, and we're both happy and sane enough to stay in it. That's not easy for everyone to do."

Other one-partner couples we found on the Internet seemed to echo Monica and Gabe's experiences.

Mike, a man Women's Health interviewed, explained his ability to feel satisfied in the only relationship he's ever had, with his high school girlfriend Becca. 

"I think if you're always looking for the next best hookup, you can't enjoy the experience you have. I don't think having more sex with other people would make me more satisfied than I am right now," he said. "A lot of people think that you need to experience everything to know what's worthwhile, but that's a losing battle. I don't feel like I'm settling with Becca. I'm not just giving up on dating because I'm lazy. I'm just happy, and I love our time together — which is a pretty clear indicator that our relationship is good."

Of course, relationships like this only work when both people in a relationship have a natural proclivity for long-term commitment and don't view sexual experiences as a right of passage.

For example, Flor, another Women's Health interview subject, said that while sex is important to her and her boyfriend of over a decade, it's not the number one priority for them. Things might be different if it was but … it's not. As a result, sex with other people doesn't really occur to them.

Other people are wired quite differently, though.

Another couple we interviewed, Reese and Adam, say they'd never be able to make their monogamous relationship work if they hadn't been with other people. They've been together for nine years of unadulterated commitment, but not before Reese — who dabbled casually in online sex work for a while — was engaged to three separate people and Adam went on a five-year one-night-stand bender.

"I think we're able to do this because we've gotten our kinks out," says Adam.  "I've experienced everything, and Reese is the height of those experiences."

Reese agrees. "I had to experiment to know what I liked. Once I met Adam, I was totally in touch with my own sexual and emotional needs, and it made me better prepared for a meaningful relationship."

Perhaps this is why Gabe and Monica wouldn't necessarily recommend their lifestyle to others, despite the fact that it works so well for them.

"This isn't for everyone," Gabe says. "Not everyone meets the person they'll be with for the rest of their lives when they're a teen. We got lucky in that sense. If it doesn't feel right for you, I wouldn't force it. Some people need diversity and experimentation. Some people don't. Neither situation is better on the whole."

That seems to be the overarching message here — that even though people whose only sexual partner is their spouse or long-term human seem to be inhumanely happy, satisfied and calm about their situations, they're only that way because they were the right people for the job. Apart from liking each other enough to renounce the rest of the planet, both parties have unique ideologies about their relationships and are willing to put in work to make an increasingly rare set of circumstances work for them. You can't force that, and it's neither superior nor inferior to other expressions of passion or love. 

Still, maybe there's something to the whole "ignorance is bliss" thing. Maybe you really don't know what you're missing if you don't know what you're missing. Nevertheless, relationships shouldn't be so much about avoiding missed opportunities … the really healthy ones are more about making the best of the opportunities you have.

And with that, we'll leave you with uncharacteristically wise Quora comment thread on the topic. In response to a user's question about whether he's missing out on other girls in his happy marriage with his wife, some sage old Internet wizard named Marcus Geduld with a successful 16-year marriage responded with this face-melter:

Of course you're missing out. And if you'd had sex with 30 girls and then got into a committed relationship, you'd still be missing out. Because there are 30 more girls waiting in the wings. In your relatively short life, you're going to miss out on all sorts of experiences.

Some folks have an extraordinary ability to live in the past, but most live more in the present. This means that if you're antsy about not-getting-to-have certain experiences, you're likely to stay that way. By which I mean that leaving your wife and then sleeping with a bunch of girls won't help — except in the short term. You'll wind up in another relationship (unless you stay single forever) and your desires to stray won't be muted by a thinking, "I don't need to. I already experienced that."

I have been married for 16 years. I still get attracted to other people. As does my wife. It doesn't help to think, "Well, I had my fun when I was younger." I want my fun now. But I also know I have a really great relationship, and I'd be devastated if it ended.

Part of being an adult is accepting that in this life, since we have limited time, we will miss out on stuff. I'm not telling you to stay faithful. I'm suggesting that "I might miss out" isn't a great way to make choices.

Mic drop. Marcus out.