I wonder if your wife's recent visit to a branch of her family made her particularly sensitive to her family's current troubles (as with nieces and nephews). Maybe she's scared of "war" between you and her family and thinks you've already declared it in some way.
This is a tough one.
Reading tea leaves is always tough. It's sort of a "more likely than not" kind of thing.
But I think "more likely than not"... that her recent contact with family and her dad returning to live close by... .play a large part of this... .and is likely "the part of this".
More later
FF