That sounds like it's a time when it's the responsibility of the manager to start communicating clearly with their colleague, rather than thinking they need to figure everything out just by looking at the situation from the outside.
Treat your employees/subordinates/colleagues like they're responsible adults, and they're more likely to act like it. That means, among other things, talking to them when you notice something that seems off, rather than just thinking it's your job as the Big Important Manager to solve all problems in your own head.
Treat them like they're bad children, or like they're all constantly looking for every way possible to get more money for less work, and you're more likely to get disinterested, frustrated, and rebellious employees. There's nothing more likely to make someone act like a child than treating them like one.