Zdad,
What does “there is a well known bulletin board website where people sell things ” have to do with whether Facebook can cause a rift even if someone does not start out seeking something for “sale”?
You are completely missing the point. It is not only someone who starts out seeking sometthing when he not satisfied. The site you are referring to, if I guess correctly is not a social site, it is a place for arranging hook ups. We are talking about social media, something totally different.