Turns out you have to actually be crazy to do a crazy thing like that …

For anyone who's ever wondered what kind of lunatic would stay friends with their ex following a breakup … here's an answer for you: lunatics. Actual lunatics.

According to a new study from Oakland University, people who stay friends with their exes are not the plain old nice people capable of maintaining a cordial interaction we thought they were.

Instead, people who continue the relationship platonically after a split are more likely to be narcissists, psychopaths and people with "dark personality traits" than the rest of us non-crazies who know well and good to stay the living heck away.

After all, those of us who are blissfully un-plagued by debilitating mental illness know that our exes are no good. Even Psychology Today has urged the public not to befriend extinguished flames because: "they are less emotionally supportive, less helpful, less trusting, and less concerned about the other person's happiness."

However, according to the study, when people exhibit these so called "dark personality traits," they have much different motivations for hanging on to a failed relationship outside of its abilities to fulfill their needs for happiness or security.

In an interview with Broadly, narcissism expert Dr. Tony Ferretti explains why people with psychopathic or narcissistic personalities would want to cuddle with the cold corpse of their dead relationship. "Narcissists hate to fail or lose, so will do what they can to maintain some connection if they didn't make the choice to end it," Dr. Ferretti said. "They can experience narcissistic injury when rejected by a partner and have difficulties letting it go or healing from it."

Add to that the fact that romantic relationships are important to psychological health. And if your mind is a little off, you're more likely to seek out relationships that cover that'll cover up your mental state.

"People who are in close, healthy relationships are typically happier, more physically active, more socially connected, live longer, and are physically healthier," Dr. Ferretti said, adding that people in relationships also smoke less and exhibit better overall health. With so many benefits, it's not surprising that someone in a compromised mental state would try to hold on for dear life to a former partner. After all, a former partner who is now a friend was still a former partner.

But for ego-maniacs, there are other benefits to relationships and motivations to cling, too. For example, a narcissist may feel as if their social status or position is amplified because of their partner, even if that partner is in friend-form. That explains why many narcissists acquire "trophy wives," Dr. Ferretti said, explaining that in the mind of the narcissist, a trophy wife is an improvement to their self-worth and confidence.

"Narcissists have a tremendous amount of pride and can't accept others being with their ex," he said. Friendship is merely a subterfuge to prevent their exes from moving on completely.

On a more psychopathic level, dark personality types are most interested in how relationships can be useful to them and that such people "may stay connected to [to exes in order to] have access to valuable resources. They also have inside information about their exes vulnerabilities and weaknesses that they can exploit and manipulate which gives them a sense of power and control," according to Dr. Ferretti.

Jesus.

So, next time your ex comes slithering back into your DMs asking for friendship, know that's probably not what they're after. In their eyes, you're of use to them whether they subconsciously know it or not, but your utility is likely not in friendship, but in your exploitability or potential as camouflage.

The best way to beat them at their own game? Totally and completely avoid friendship following a breakup unless you're 100 percent sure that bowl they're holding wasn't whittled out of missing person's skull. Good luck!