A message arriving late can meet a different person from the one it was written for.

Words are aimed at a person as they were at the moment of writing. If they arrive weeks later they land on someone who has already grieved, decided, forgiven or hardened, and the message no longer fits the person holding it. Neither party did anything wrong. Time simply moved one of them.

When a reply comes late, allow that it may have been written to an earlier version of you. And when you delay sending something, consider saying briefly where you were when you wrote it. A little context lets the other person receive it as it was meant.