5 Tiny Things Secretly Determining Who You Have Sex With

5 A Man Can Get Erection Issues If His Partner Is Too Close With His Friends

For many straight men, the Holy Grail of relationships is the cool girlfriend -- the one who is not only completely fine with all of his hobbies and various vices, but who also gets along with all of his buddies and loves to hang out. But then, an odd thing can happen: The guy -- who gets exactly what he wants -- suddenly finds his boner disagrees.

Yes, we're saying that a man can be visited by the Erectile Dysfunction Fairy if his partner is on particularly good terms with his posse, and yes, we've got the science to back it up. The phenomenon is known as partner betweenness, and it appears to have something to do with traditional gender roles. Specifically, how much he feels like he controls his lady.

It's not so much that he automatically believes she's banging all of those guys behind his back -- like everything with gender and relationships, it's more complicated than that. There are a whole bunch of complex, unspoken rules in any social network ("Wait, you invited Steve to the party but not me?") and those rules follow you everywhere, including the bedroom. What the research found was that males are taught they need three things in their relationship with a woman: autonomy, privacy, and control. To put it bluntly, she may be a member of the group, but she "belongs" to him.

If she has more contact with his friends than he does -- even if it's not sexual -- then those three things are threatened and he feels like less of a man. How much less? Enough to increase chance of erectile dysfunction by a whopping 92 percent. It doesn't affect everyone (affecting about 25 percent, in their estimates), and it gets better with age and maturity, as the guy slowly figures out that a lot of what he had heard about masculinity was bullshit spouted by insecure grown-ups.

4 The Size And Cost Of The Wedding Affects The Marriage (But Not How You'd Think)

If we have our stereotypes right, the average woman has a "dream wedding" in mind that involves a huge crowd, six figures worth of decorations, a flock of doves, and the groom riding up the aisle on a white stallion. Meanwhile, the stereotypical male would be happy with a "wedding" that involves clicking the "married" box on Facebook from home and calling it done. After all, why go through all of that trouble when none of it matters in the long run?

But it does matter, for what turns out to be some pretty cynical reasons.

First, The National Marriage Institute found that people who have bigger weddings report a higher level of marriage satisfaction over the first five years, and "bigger" is measured purely by the number of guests, not cost. That result is supported by another study that shows that the larger the wedding, the less likely it will lead to divorce. Some numbers: Weddings with only one to 10 guests are almost three times more likely to end in divorce than weddings with more than 200 guests. Hell, even a decent-sized wedding with 11 to 50 guests is still twice as likely to end in divorce compared to the 200-plus wedding, so we know it's not just those spur-of-the-moment drunk Vegas weddings skewing these numbers.

The theory is that larger weddings provide the couple with added support -- or pressure, if you prefer -- to stay together. In other words, you've invested in your relationship, and you want to protect your investment.

"Okay," you say. "So, the solution to an eternally functional relationship is throwing money at a huge wedding. That sucks, but, hey, at least we know one exists. That has to count for something."

Wrong again! You really should stop walking into these obvious traps, narratively convenient person we just made up. Shockingly, a huge money pit of a party that can potentially wreck your -- and, worse, your parents' and in-laws' -- finances is not the best way to enter forever after, either. So, as a final twist of fate, that exact same study also found that the more you spend on your wedding, the more likely you'll end up divorced. Weddings that cost less than $1,000 are about half as likely to end in divorce as ones that cost between $5K to $10K, which in turn are roughly two-thirds as likely to end in divorce as weddings that cost more than $20K.

The lesson is clear: If you want a statistically foolproof marriage, invite every person you know, but somehow keep the budget under a thousand dollars. This may seem depressing and even impossible, but look on the bright side: If you manage that, chances are you have a lucrative new career as the world's best party planner ahead of you.

3 A Style Is Only Sexy Until Everyone Starts Doing It

Let's use beards as our example.

If you think beards are awesome, you're in luck because America has jumped in the Beardmobile with you. The burly lumberjack look and the scrawny hipster it's replacing are both beard-heavy styles, so until the world inevitably grows weary of the phrase "lumbersexual," plenty of previously well-groomed guys are deciding to try out the rugged, "might wield an ax but in a totally non-murderous way" look. But, science says that by so increasing the world's beardiness, we're ruining the charm of the beard.

A 2013 study found that women rate men with heavy stubble as the most attractive, leaving both full-bearded and clean-shaven men behind. Still, guys, don't invest on that Don Johnson stubble trimmer just yet -- another, even more recent study from 2014 complicates the matter even further by indicating women find both beards and stubble preferable to a complete lack of facial hair. However, there's a catch: This only works when beards are rare.

The researchers figure that although women can still find facial hair attractive, its true sexual magnificence can only be unleashed when the majority of men don't have beards. And, thus, you have the paradox that comes with trying to make sure your look is fashionable. We tend to judge a person's attractiveness by comparing them to others, and, by sporting a popular and common look, a dude signals he may not be that special after all.

So, you would assume that the truly fashionable male knows the exact sweet spot to hit when crafting his look. Basically, you should get in on it when it's still on the rise, but bail out before every party looks like ZZ Top cosplay. If you're the type who reluctantly jumps on trends only after every single one of your friends is on board, you might as well just wait it out.

2 A Recovered Sex Drive Can Lead To Divorce

Imagine you're John Q. Nobone, erectionally challenged 50-something, who finally musters the courage to walk into the doctor's office and ask for a prescription of Viagra. After poppin' a pill, you magically regain your sexin' and promptly take it to your wife, Norma. She gets some, and you get the overwhelming rush of being able to perform once again (and, of course, also some). There are only winners in this equation.

Or are there?

Although Viagra tends to be seen as a universally wonderful thing (provided you don't buy one of those Chinese knockoffs made of Smurf paste and ground fox anus), the newfound bone prowess it brings has plenty of pitfalls, even if you're completely faithful to your spouse (something not all Viagra users manage). In fact, according to a report by the Harvard School of Medicine, using Viagra can actually increase the chances of divorce.

There are no specific figures, presumably because few couples cite "all the sex" as grounds for going their separate ways, but marriage counselors insist the pattern is there. The problem is that the sudden change in libido can lead to hurt feelings and outright resentment. Especially in older couples, where the wife will have lost some of her own sex drive, the husband's renewed interest -- and a newfound ability to capitalize on said interest -- can force the couple to confront sexual issues they have long grown into ignoring. He may not have been able to get it up, but she might actually have been perfectly okay with that. As a result, she might not welcome the return of regular sex, especially if the 20- to 30-minute sessions from back in the day have suddenly turned into chemically-induced two-hour wear-and-tear marathons.

As such, doctors caution that performance-enhancing pills should be taken with a heaping side of open communication. After all, sex is a thing both parties should benefit from, so it's pretty damn essential they're on board with the idea of an upgraded husband.

1 Our Sense Of Smell Controls Attraction In Lots Of Bizarre Ways

As the perfume industry is fond of reminding us, the sense of smell plays a role with who you are attracted to. We've previously described how a person's natural aroma helps your subconscious mind decide whether you can make healthy babies with him or her. What you may not realize, however, is just how big a role your nose plays in the relationship game.

Science has started to discover that smell is not so much a one-dimensional bit player in your love life as it is a particularly obnoxious director, manipulating you to desired effect like an olfactory Stanley Kubrick. And we mean manipulating. For starters, your sense of smell can and does trick you into believing people are better or worse looking than they objectively are. It doesn't give a hot, steaming shit about whether the nose-boner it's getting from olfactory cues comes from a natural or artificial source, either: According to research, a good perfume (or cologne, as this applies to both sexes) will make the wearer's face appear more attractive to the smeller, and the large helping of pepper spray you'll get after leaning too close to smell said perfume would likely have the opposite effect -- even if you weren't busy rolling on the floor and whimpering.

And that's just the beginning of the many relationship-related nasal superpowers we all have, whether we're aware of it or not. Many animals use smells to communicate, and there is an increasing amount of evidence that, although our brains tend to keep it at a subconscious level, humans aren't any different. If your sense of smell isn't working, you tend to have fewer relationships (guys) or be a whole lot more insecure in them (ladies).

This may be because the nose actually seems to be a pretty damn important relationship tool: The longer a couple has been together, the more accurately each individual can tell if his or her partner is relaxed or stressed just by the scent of the other person's sweat. Women's noses are particularly good at sniffing out potential relationship issues, if in a heterosexual relationship, as they are able to detect fear, disgust, and sexual arousal in a man's scent. Perhaps as the strangest example, the results of one 2014 study seem to suggest we may be able to recognize other people's political beliefs from their body odor and gravitate toward the ones closest to our own most alluring. Incidentally, many of these scent-emotions are also highly contagious, which researchers speculate could be our way of rapidly communicating emotions in larger crowds. Yes, science is saying humanity is basically a sweat hive mind.

Note: This does not mean that you should ever say to your significant other: "Honey, are you okay? You smell super pissed."

If science messed up your love life, Dennis is the creator of LemonVibe, an anonymous relationship advice site. He blogs and tweets, too.

For more relationship advice from Cracked, check out The 4 Easiest Ways to Accidentally Ruin Your Relationship and The 5 Least Romantic Keys to a Happy Relationship .

And to further expand your noggin, check out Cracked's De-Textbook: The Stuff You Didn't Know About the Stuff You Thought You Knew.