No One Has Ever Met Anyone
When you think you are touching a table, you are not touching the table. The electrons in your fingertips and the electrons in the table refuse to share the same space, and the resistance you feel is that refusal. There is no atom to atom contact. The whole sensation of "touch" is a force telling you that contact has been declined.
You have never touched a single thing. You have only ever felt things refusing to let you in.
Knowing another person works the same way. You have never met anyone. What you have done is intercept signals that came off them, words, expressions, gestures, tone, the heat of their attention, and assembled, inside your own head, a working model of someone you call by their name. Then you mistake the model for the person.
The signals are not the person
Every signal is a translation of something internal into something external. By the time it reaches you it has already been compressed, edited, performed, filtered through a body and a culture and a moment. Then it crosses a small gap of air, gets resampled by your senses, and is reconstructed by a brain that is mostly running on prior expectation. What arrives is a version of a version of a version. The original is still over there, sealed inside the body that produced it. You did not get it. You got the postcards.
We do this without noticing
The startling thing is not that we do this. It is that we do not feel it as a gap. Our experience of "knowing" someone is seamless. There is no felt distance between the model and the person. That is why finding out we were wrong about someone is so disorienting. We were not wrong about the person. We never had the person. We had the model, and the model just got an update.
Why the comparison to touch matters
The atomic case makes the relational case bearable. It is not a moral failure that we cannot make full contact. It is the structure of being a body in a world of other bodies. Forces hold us close enough to interact and far enough to stay distinct. The same is true of minds. The gap between you and another person is not a tragedy. It is the only reason "you" and "another person" are two things at all.
What changes when you see this
Not much, and everything. You still talk to people, still care about them, still feel met by them sometimes. But you stop confusing the sense of knowing with the fact of knowing. You become gentler with the model, because it is yours and it is incomplete. You become more curious about the person, because you finally notice they are still over there, still sealed in, still mostly unmet. And you stop being surprised that the people closest to you are also, in a real and physical sense, the ones you have never quite reached.