The person who keeps a private confidence has protected a relationship beyond the conversation itself.

Discretion works quietly and is only ever noticed when it fails. Keeping something to yourself does not just protect the one fact; it protects every future conversation, because the person learns that talking to you is safe. Repeating it, even kindly, even to one other person, closes a door that will not reopen, and usually the teller never finds out why the friendship got shallower.

When you feel the pull to pass something on, notice what the retelling is actually for. It is nearly always about being interesting rather than about helping. If you are unsure whether something was told in confidence, treat it as though it was.