Does Facebook ruin relationships?

[MusicMan]

With social networks such as Facebook and other sites such as Twitter, do you think these sites could potentially ruin or break apart people's relationships?
I have quit Facebook for a number of reasons but one of the main ones was like most couples were always arguing on their walls for everyone to see and there is always that dilemma to whether or not to update your relationship status etc.

Have you ever been in a relationship with someone who you have on Facebook and how did you find it? Would you rather have them on your phone rather than a social network?
Please give me your opinions, Thanks!