Why do I feel guilty for hours over a stranger I'll never see again?

Here is what happens. You snap at a server, or walk past someone without a word, or say something clipped to a stranger. Then for the rest of the day, it replays. You will never see this person again. There is no apology to give, no relationship to mend. And yet the guilt keeps running, like a debt with no address to send payment to. Guilt is supposed to be useful. It points you toward a repair you can actually make. But when the person is gone, the signal has nothing to attach to, so your mind keeps recalculating the same sum and never reaching zero. This is not about them. It never was. It is about the gap between how you want to treat people and one moment where you did not. That gap deserves a clear look — not three hours of quiet punishment.