all other questions and conversations are off limits due to Tznius reasons.
It shouldn’t even have to come to that. No one has to justify why they don’t want to answer personal questions. If your wife doesn’t want to deal with him anymore, she should just very sternly tell him that she does not socialize with men. That should be the end of it.
If it still goes on, then she has a valid complaint to take to the employee’s supervisor.
The Wolf