It takes a certain type of person to have their relationship ruined by Facebook—be it weak, insecure, crazy. Facebook, like marriage, only solidifies what you already have. Facebook doesn't ruin your relationship, it just heightens the problems in it. If you date a dude who's "flirtatious," Facebook just puts in your face what he's really doing behind your back: flirting. If you date a girl that is crazy/insecure, Facebook just puts that in your face. You'll see more of her insecurity come out when she's asking about every girl who posts on your wall, likes your pictures, and invites you to play Tetris Battle.
This is irritating to me because if we allow you to blame Facebook, then you never have to take responsibility for your actions and your mess of a relationship. Let's be clear; even if you take your relationship offline, that's not going to change the fact that it is a hotmess.com. Stop blaming Facebook and take some accountability. Just like Facebook isn't responsible for the fights and murders that ensue as a result of online beefing, neither is it responsible for your sham of a relationship. Get your life together!