A goodbye spoken kindly can still leave both people wanting another minute.

Doing a farewell well does not make it complete. You can say the right things, say them warmly, be genuinely glad about the visit, and still stand there afterwards with a sense that something remained. That is not evidence the goodbye failed. Endings are rarely the right length, and kindness makes them gentler rather than sufficient.

If a parting has left you unfinished, send the extra minute later in whatever form suits you. And when you next say goodbye to someone you will not see for a while, let it run slightly longer than feels necessary.