Anyone who's ever been in a romantic relationship has met the green monster known as jealousy. He's a real piece of sh*t. He nauseates you, makes you cry and turns you into an awful, irrational, angry person.
He creeps up on you everywhere -- in the presence of opposite-sex friends, when you're innocently browsing your Facebook news feed and sometimes even when you're talking to your boyfriend's mom.
It's normal to experience jealousy, and it's even more normal to experience it in a variety of different ways.
In fact, researchers David Frederick of Chapman University and Melissa Fales of UCLA recently conducted a study attempting to confirm the long-standing idea men experience more sexual jealousy (regardless of whether or not an emotional connection took place) and women experience more emotional jealousy (regardless of whether or not sex was involved). And they were successful.
Studies that had previously attempted to explore this idea had only been conducted among small, exclusively heterosexual communities.
Frederick and Fales, on the other hand, compiled data from almost 64,000 heterosexual, homosexual and bisexual men and women, aged 18-65.
They asked participants if they'd be more upset if their partners slept with someone but didn't fall in love with him/her, or if their partners fell in love with someone but didn't sleep with him/her.
The results showed straight men comprised the only group of people whose majority (54 percent) said it'd be more upset over the idea of their partners having sex without love.
Only 35 percent of heterosexual women, 32 percent of gay men, 34 percent of lesbian women, 30 percent of bisexual men and 27 percent of bisexual women felt the same.
For an explanation of heterosexual couples, researchers looked to evolution. Before DNA testing, a man could never be sure if a child he was helping a woman raise was his own child.
Of course, raising a child is a lot of responsibility and a huge commitment, so -- evolutionarily speaking -- if the child wasn't his, it wasn't exactly worth it to stick around and help the woman.
So it makes sense a man would be more upset by a woman who may have had sex with another dude: He could have been putting his precious energies toward raising a kid who was actually not his. Not worth it if you're thinking only evolutionarily.
Again, evolutionarily speaking, women fear the man helping them raise their children will abandon them, leaving them to raise their children alone.
If a man isn't emotionally attached to a woman, he's far more likely to leave, and an emotional attachment to someone else would make him even more likely to leave.
While certainly convincing, it's not enough to just look at evolution to explain these differences. So researchers also examined the role modern-day definitions of masculinity and femininity play in these different experiences of jealousy.
Today, a crucial aspect of being a man is having lots of sexual prowess. Therefore, if a man's partner has sex with someone else, he'd question his ability to satisfy his woman in the bedroom.
In this way, the very core of his masculinity would be challenged, which is certainly jarring. It makes sense a man would be more upset over a sexual threat than an emotional one.
On the other hand, a crucial aspect of being a woman is being nurturing and emotional.
If a woman's partner falls in love with someone else, she'd question her core feminine ability to bond: to feel emotions and have them be felt for her in return. For a woman, an emotional threat is far more damaging than a sexual one.
These results don't mean men are never jealous of emotional attachments or women are never jealous of sexual relations.
Of course, men still experience emotional jealousy and women still experience sexual jealousy. In fact, the study poses a variety of different theories demonstrating why the opposite is true, too.
One reason points, once again, to gender norms. In addition to being taught to be nurturing and emotional, women are taught to be sexually desirable.
If a woman's partner has sex with someone else, she'd feel like she failed to be desirable enough for her man, severely lowering her self-esteem and body image.
The explanations behind the results of homosexual and bisexual couples were a bit uncertain. The study points to sexual infidelity as more normal among the gay community, so they've been taught to suppress or ignore those feelings of sexual jealousy, leading to a focus on emotional jealousy.
Homosexual couples also don't experience the same evolutionary reproductive obstacles heterosexual couples do, so they never developed those same aforementioned differences in reasons for jealousy.
This explanation, while reasonable, was challenged by bisexual men, even those who were in relationships with women, had a similar response to the survey as homosexual men did.
The biggest take-away from this research is jealousy sucks. It doesn't matter if your boyfriend liked a picture of a pretty girl on Instagram or if your girlfriend is still best friends with her ex -- in all of its forms, jealousy is a cruel, cruel force ripping people in half and tearing apart relationships.
You can, however, take comfort knowing a bit of jealousy is actually healthy for your relationship. Biological anthropologist Helen Fisher tells CNN jealousy can "wake you up."
It reminds you your partner is good-looking and desirable, motivating you to be nicer and friendlier in your relationship.
So, it looks like if you want to relight the flame -- instead of, you know, upping your game in the bedroom or doing something nice for each other -- you can try purposely making your partner a little jealous.
It certainly seems scientifically recommended. Morally, though, you probably shouldn't.