Spouse leaving court with no claims

[Madae]

What is it that causes a spouse to just randomly leave court when they have no claims? I had my son betrothed and married, but after a year or two, she just decided to move back to her home and left my son with no kids. Didn't play long enough to find out if she could be invited back by him once he inherited, but I had a feeling she would have to be divorced eventually.

 

[Emperor 1997]

What is it that causes a spouse to just randomly leave court when they have no claims? I had my son betrothed and married, but after a year or two, she just decided to move back to her home and left my son with no kids. Didn't play long enough to find out if she could be invited back by him once he inherited, but I had a feeling she would have to be divorced eventually.

Bug since Release.
It is caused by the automatic Resettlement of every Close Relative, whenever a Close Relative becomes an Ruler and yes, this includes Adventurer too.

The only way to prevent it, is giving your Childs at least a Barony Title, because then they are an Ruler and their Spouse is the Spouse of an Ruler and is now excluded from the Automatic Resettlement.