Ace5
Recruit
It has happened a couple times, and I had to restore to a previous save once to fix it. I go to a town and the first thing I do is set my Wife as governor (both times it was the first thing I do), then I waited for a bit. I went back and it showed governor as none, I checked the keep and she was not there. I check the encyclopedia and it says she was last seen at the town two days ago. After about 3 days of waiting and trying different things, I check the encyclopedia and she has traveled to a completely different city, that is quite far away. Looks like a bug to me .