“Whatever” ends more conversations than “goodbye” ever has.

One word can close a door more firmly than an actual ending does. Said at the wrong moment it tells the other person you have stopped engaging while giving them nothing to answer, which is why it stings more than a plain argument. It is usually self-protection rather than cruelty, a way out of a conversation that is going badly. The trouble is that it leaves nothing behind to repair.

The moment you feel it coming, say the true thing instead: that you are annoyed, or tired, or need a minute. If you have already used it on somebody, go back and finish the sentence you skipped.