What to say when a guy says my friend suck on facebook?

[Pernille]

A guyfriend of mine commented on a post by a friend of mine, saying she sucks. Basically, she ruined her phone and he just commented it. I know that they have troubles in the past and that the guy is very hurt, but I don't want my friend to get hurt.
What can I comment back? Anything? Thanks

[to]

Actually wouldn't it be kind of rude to butt in?
If she thinks he's going out of line, she can delete his comment/unfriend him/block him.
It's a problem between them to begin with, so unless you know(not guess or imagine) a way to actually help, wouldn't your intruding add to their problems by creating further tension between yourself and him?

[Yinzer]

Unfriend and then block him from your face account.