To my mind this ceasing of looking up the parents is significant and 'means' something... but what!?
I wonder if she had incidentally come off FB for separate reasons? For example, a lot of people migrated off FB a few years ago when it became mainstream news that FB was tracking and influencing algorithms and mining one's data, plus it went out of fashion with the younger generation. Also depending on what device she was using, a lot of people took FB off their mobile phones due to the advancement of things like WhatsApp and SnapChat. Plus the amount of space it takes up.
Maybe she just deleted the app off her phone and then didn't do it any more?
JMO MOO