Some relationships arrive quickly. A glance, a few late-night conversations, and you feel that you have finally been seen. That hidden part of you, the part even you are not quite brave enough to confirm, has finally been given a name by someone else.

Then comes the fading. The gaps between messages grow longer without either of you quite noticing. Enthusiasm becomes a balloon slowly losing air. Each day, you can only feel it shrink a little, so little that you are not sure whether it is only your imagination. Until one day, you scroll back through an old conversation and realize that the person you were a month ago and the person you are now seem almost unrelated. You cannot point to where things went wrong, but you know clearly that something is moving away, irreversibly. It will not come back.

There is nothing here to blame. When two people move closer, they always stop at some distance. Some people stop at the level of the body. That is not meant as an insult. It is simply true. That kind of attraction has its own complete rhythm, from beginning to climax to ebbing away, precise as a law of nature. It simply cannot go any further.

We know this very well. Novelty has an expiration date, and the part of one person that can keep another person feeling renewed will eventually be used up. The moment it runs out is when the real problem begins. It is not that the other person has stopped being interesting. It is that you discover you do not know what else a person can rely on, besides being interesting, to remain in someone else's life.

Modern life has taught us a rather efficient skill: replacement. Replace one person, one relationship, one possible future with another. This is not depravity. It is simply the natural response to having too many options. When every relationship can be so easily replaced by the next, why spend so much effort on one person? No one builds a road to a spring for a bottle of water that can be bought anywhere.

But this is not a criticism of anyone. We have simply been spoiled by excessive possibility. Every relationship begins to feel like a sample packet. When one is used up, the next is already within reach. The logic is almost flawless. Its only weakness is this: there are some things a sample packet cannot give you.

What kinds of things? You will not know until you have seen someone sit beside you at your worst. Not gentle comfort. Not a few lines of "I understand." Just sitting beside you, saying nothing, doing nothing. Simply not leaving.

There is an old couple on that street. The husband has trouble with his leg and walks very slowly, with a slowness that carries a quiet endurance. His wife walks beside him, her pace unconsciously slowing until it matches his. They do not speak. They do not look at each other even once. And yet you can feel, with absolute clarity, that there is an invisible thread running between them. It is not passion; passion cannot burn for that long. It is not responsibility; responsibility is not that soft. It is not even what we usually call love. That word is too light. It cannot hold so many years of wear and silence. It is something heavier. Like water seeping into stone year after year, until eventually you can no longer tell whether it is water or stone.

They must have argued. They must have thought, more than once, about giving up. There is no need to ask. Those moments did not separate them, not because either of them was especially strong. Rather, over all those years, a third thing had grown between them. It was not one person's persistence, nor two people's compromise. It was something planted by time itself. You cannot speed it up, and you certainly cannot manufacture it by force. The only way is not to leave, and to wait for it to grow on its own. And it may not grow at all. You may wait for many years and receive nothing. That is the hardest part.

So perhaps the question is not how to make someone stay. It is the reverse: whether you are truly prepared to let another person's weight take root in your life. Roots grow slowly and invisibly. For a very long time at the beginning, you will feel as if nothing is happening at all. By the time you can truly feel them, you can no longer tell which parts are yours and which parts are the other person's. This indistinction is not a loss of self. It means your world has already been rebuilt once for someone else.

None of this is romantic. It should not be called romantic. It is rough, ordinary, worn down. It is two unexceptional people, caught in countless impulses to turn around and leave, and neither of them taking that first step. They remain only because they did not go.

The pleasure the body can hold has its precise boundaries, and that limit was written long ago, with a strictness almost cruel. But when two people have stayed together long enough, something else may grow beyond those boundaries. It has no name, and it does not need one. It is simply there. You cannot touch it, but you know it exists. Just as you know that between that old couple, there is a kind of silence stronger than all language.

Exact date of writing unknown; Translated from the Simplified Chinese original.