In the aftermath of his Twitter fight with Wiz Khalifa, Kanye tweeted this: “Me and my wife got the kind of love that can turn exes into best friends.” While this kind of love may be true for the likes of Gwyneth and Chris, mere mortals who were unable to book a Super Bowl halftime show last weekend will have to work a little harder.

Staying friends with exes can be an act of self-preservation. Exes, after all, are people we once gave pieces of our hearts to. When those relationships end, what becomes of those pieces is what becomes of a smartphone left unattended in a crowded place: it gets lost. And once they’re gone — the people, the pieces — who’s to say you’ll ever get them back?

The older I get, the more I realize how hard it is to find people I really connect with. One hundred and one Tinder matches don’t add up to 101 people to talk to; it just adds up to 101 awkward handshakes… or whatever the kids call it these days. Finding people who know the incognito search histories of your soul but still want to talk to you anyway is rare, so why should you let a little thing like heartbreak get in the way of possible long-term friendship?

The simplest way to look at exes is by going back to our high school geometry lessons about the Cartesian Plane: exes are the constants in a world full of variable whys. Exes are like the airplane black boxes of our lives — recording vital information about what went on before a crash that help us answer all our unanswered questions. They are time capsules of different phases in our lives that easily remind us of our favorite songs, movies, books and outfits. They are hard drives of our past selves before all the software updates and system crashes. They are road signs that serve to warn us about what kind of a-holes we can be when given the chance.

The key to successfully keeping an ex in your life relies on many different things. The first is something I like to call The Mutual Needs Theory. TMNT (yes, like the turtles) stipulates that you and ex need to be able to mutually benefit from said “friendship” or “whatever-this-isness.” Psychologist Abraham Maslow says that our needs ascend from basic physiological (food, water, sex, WiFi) to self-actualization (morality, creativity, problem solving, picking the right profile photo).

The second has a lot to do with time. For the sake of argument, let’s say that there are two kinds of time that exist. The first is called real time and it moves as it should. It is rigid, mechanical and predictable. It follows the ticking of the clock, the movement of the earth. Everything is at it should be. Your pizza arrives within 30 minutes or you get it for free.

Einstein’s Theory of Relativity stipulates that time isn’t a fixed unit for everyone, that it moves differently for different observers. It is “relative.” This explains the second kind of time, or ex time. It moves slowly and can’t be measured. It makes itself up as it goes along — slowing down or speeding up as it pleases. No past, no future, only moments.

Art by Sean Eidder

It is in this kind of time when our “I can’t sleep” messages are possible. It is the kind of time when we can finally admit defeat, lay our failures out on the table, and know that whatever is said here won’t matter in real time. This time calls for honesty, spontaneity and sweeping romantic statements. It’s a time when we get to speak to the moment knowing that none of this will change the past or disrupt the future. It’s a time to talk about our grandest dreams and worst food allergies knowing that when we run into them in real time, we will be strangers who grasp for things to say to each other.

If there’s anything Christopher Nolan has taught us, it’s that playing with time does have consequences. After spending countless nights in ex time, we will find ourselves waking up wondering why we’re so tired, and where those dark circles under our eyes came from. We will look exhausted and aged with no experience to show for it. This is when we realize that we ultimately have to pick sides in the battle between our “for nows” and our “forevers.”

The need to rationalize friendships with former lovers through scientific theories and diagrams is what makes them exes in the first place. Because navigating through the kind of love that remains when passion is lost is the sort of problem that takes centuries to sort out. While some of us are lucky enough to sort through the mystery, others may just rely on this age-old adage from Amber Rose: “We once loved each other, so I won’t do you like that.”