Science Fact: Men who feel their relationships are threatened are more likely to react with aggression; women are more likely to react with avoidance.
Explanation: Being in a relationship is basically the worst (except for not being in a relationship). Every fight is a confusing ordeal, in which it seems like the other person is doing exactly the opposite of what a human brain would do, specifically to confound you. Arguments often go like this:
Girl: Why don't you want to come out dancing tonight?
Guy: Aaargh! Dancing is a dumb as a moron, just like your face, which is an idiot!
Guy: (Slams the door, or, if no door is available, stomps very far out of his way to slam a completely unrelated door)
Guy: Did you see Kelly's new car?
Girl: ...No. (Walks into another room for no reason)
Guy: (Following) Are you okay?
Girl: ...Yes. (Walks into yet another room)
Guy: What is wrong with you??
Girl: (Walks into a broom closet)
If you've ever been in a weird semi-fight where you don't even understand what the problem is, but there obviously is one, you are familiar with vignettes like these. The other person basically starts acting like an alien. But (s)he is not an alien; (s)he is merely reacting to something called fear of negative evaluation. Note: disregard post if dating actual alien.
The Science: "Fear of negative evaluation," or FNE, is the term psychologists use for when you think that the other person is about to think less of you somehow. If you are a dude, and it is physically impossible for you to dance without repeatedly injuring yourself and others, you might feel this if your girlfriend often wants you to go dancing. If you're a girl whose boyfriend hangs out with other girls, you might feel it if he often talks about them or is always noticing stuff about them.
A recent study found that this fear plays out differently for men and women; men tend to get aggressive when they feel threatened in this way, and women tend to get emotionally distant. Furthermore, the study found that this stuff happens regardless of relationship quality. That is, it's not just the couples who are always fighting and who are clearly terrible for each other that do this stuff; it's everyone.
So What Should I Do About It?
Step one is to be aware that FNE fights are often irrational, and there's probably nothing to feel threatened about, unless one partner is constantly dropping very ominous hints. ("Knock knock!" "Who's there?" "Orange you glad I want to break up with you because you are awful.") And no matter what precipitates them, our reactions to feeling emotionally threatened are also rarely reasonable. A girl constantly taking imaginary texts to avoid discussion or a guy who pointlessly throws the toaster out the window are not acting in a way designed to resolve a problem.
Step two is to realize that you do this too. Every person does. So unless you are a robot or a houseplant, this post isn't about Crazy Things The Other Gender Does.
Step three is resolving stupid fights. If you're the one who feels threatened, you need to explain why, with the calmness of a saint and the non-craziness of a sane person. If the other person is the one acting nuts, you need to find out why, with the same calmness and saneness. Most of the time, people aren't being intentionally belligerent or distant; they're just worried about something, and all you need to do is figure out what it is.