My previous reply to this was deleted for not including a link - sorry about that! According to
this article, the stepfather stated that the mom blocked him on social media:
On Facebook, blocking someone while your relationship status is linked to their profile will result in what you saw, so I'm guessing she took a single action (blocking him) rather than going to the effort to change her relationship status as well. Personally, I'm much more interested in why she blocked him and left the area than the relationship status change.