Some of it stems from religious zealotry (marriage is sacred and permanent).
Some of it is a misguided attempt at rectify the 'single parent' problem, believing that two unhappy parents is better than one parent divorced.
Essentially if you make divorce harder, more couples will be forced to work through their disagreements and reconcile.
I think the feature is cool and I'm looking forward to it personally.
Maybe they should have made it opt in, but social features like this on other platforms like discord and stream aren't, so .. eh.