These conversations don't work in the same way that conversations about why you declined to hire someone don't work. They always push into negotiations between

These conversations don't work in the same way that conversations about why you declined to hire someone don't work. They always push into negotiations between the decider and the person who didn't like the decision. They have decided to leave, that is that. If you want to avoid these things in the future, a reasonable strategy is to be really clear in setting expectations of the people who work there and the metrics by which they are evaluated. Then check in with them regularly and talk about both of those things. That will keep the employee and the manager on the same page and it will be a surprise to neither of them when things change.