The person asked to keep confidence has accepted work as well as information.

Being trusted with something is not free. From that moment there are conversations to steer away from, an expression to manage, and a low ongoing weight in the background, especially around people who would want to know. It is genuine labour, usually unacknowledged, because whoever asked counts only the telling. Confidence is a job with no visible hours.

Before asking somebody to hold something, consider what it will cost them and whether they are the right person. If you already carry one, finding it heavy is normal rather than disloyal.