To Wolf:
The thing is that on FB, all those who are “friends” in the Facebook sense are not necessarily “friends” in the sense of a friendship the way we would think of one outside of Facebook. Therefore, the jealousy issue is a real one.
Beyond that, IMHO, if a chosson-kallah are from those groups in klal Yisroel that hold of communication during the engagement, they still should not be doing it on Facebook. This is a relationship that’s in a very delicate stage; way too easy to mess it up like that.