According to the Daily Telegraph, Facebook is being cited as a factor in 20% of marriages that break up. According to British divorce lawyers, social networking sites are tempting people to cheat on their partners. Apparently bored spouses look up old flames and rekindle former relationships, in addition to flirting online.
I have to confess that I have looked up a few of my old boyfriends online, but purely for curiosity. I actually looked up my very first boyfriend, another Catholic named Mike, on Facebook about a year ago. I even sent him a message to say hi, but I most decidedly did not "friend" him...who knows what kind of a person he is!
In my case, I experienced some sense of satisfaction over that encounter. He's divorced and unhappily remarried. He actually apologized for the way he treated me (said he was a jerk, which he was, when he dumped a bucket of water over my head as I was walking home from the bus stop, after I refused to get back together with him).
I did friend another guy I knew in college--not a boyfriend but a fling--but soon defriended (unfriended?) him as I realized that he wasn't someone I wanted on my friend list.
My guess is that if Facebook really does contribute to the breakdown of marriages, they were in trouble to begin with. In my case, Facebook has only served to confirm that I made the best decision of my life 20 years ago when I said my vows!