I just found some more information about how Facebook is straining relationships: A Canadian study came to the conclusion that the more you use the site, the more likely you are to become jealous.
It's hardly surprising. The whole essence of social networking is that it makes visible online what are mostly invisible offline: people's social connections with others.
So if your wife innocently talks to a male workmate at a party, you might feel a twinge of jealousy while you see the interchange occur. But you'll probably forget about it pretty soon afterward. And you'll never see the numerous other chats that the two have at the water cooler simply because you're not there.
However, if you notice some communication occurring between the two online on Facebook, it's there in black and white. And it's probably all there, too! If you had any suspicions at all these could easily be magnified by the visibility of this relationship. No wonder many people end up thinking the worst about their partners' feelings for their Facebook friends, and why they often remain so steadfast in their delusions.
It's yet another reason to treat Facebook with caution, and to get away from it occasionally if you're using it alot.