Or it's their way of showing that they just love other people's misery.
There's a lot of things on Facebook that there shouldn't be. The "like" button on break up statuses, annoying game notifications, my mom...
It's usually just a very impersonal way of sympathizing for them.
It could be acceptable if they were in a bad relationship and unhappy, you could be 'liking' that they finally got away from a terrible person
It's fucked up when*
good correction lol
I've always thought of it like a "there, there" pat.
I've always hated when people do that.