I’m not sure why some people do this, but the counter is to be visibly uncomfortable and keep your reactions short. People engage when you engage, for the most part. When they cross a line, keep it at “I see.” and don’t ask for more details. You might appear aloof but I guarantee that the rest of your colleagues have learned similar defense mechanisms to avoid the same conversation.

Pretend you’re their boss’s boss - how would he or she react if an employee trauma dumped?