The problem with marriage, we all know, is the endlessness of it. Plenty of things we do will have long-term repercussions, but in what other situation do you promise to do something for the rest of your life? Not when you choose a college. Not when you take a job. Not when you buy a house. During childhood, you pick up many habits that are probably going to be lifelong, like walking, talking, reading, and sleeping, but once you’ve got those down, you start to feel like you’re at greater liberty to decide what things you want to do and what things you want to stop doing. Especially when you’re a young adult the apparently infinite multiplicity of possible choices—possible jobs, possible friends, possible cities, possible girlfriends or boyfriends—can sometimes fool you into thinking you have an infinite amount of time to try out everything. But once you’re married, you’ve significantly cut down the options, and it suddenly makes your life feel shorter—like now there’s a direct line between you and your own death. You’ve just gotten on a train and you won’t get off until the very end of the track. In your final moments, if you stick to your promise, you’ll still be doing the same thing you’re doing now, dealing with the same person, possibly having the same arguments. And that commonality between now and then makes that far-off time, when you’re old and sick and about to die, a little more imaginable. Which is scary.