Nothing rests easier than a conscience that already said sorry and meant it.

An apology that was actually meant closes something. Until you say it, the thing sits there and you carry a low background awareness of it: the person you avoid, the subject you steer around, the small flinch when their name comes up. Getting it said is not really about being forgiven. It is about no longer walking around it.

If one has been sitting there, keep it short and specific. Name what you did, say it was wrong, and skip the reasons and the request to be reassured. Whether they accept it is theirs to decide, and the part that lets you sleep is the part you control.