Privacy Boundaries in Relationships

In todays society we are all somehow connected to technology. Whether it be cell phones, email, social networks, caller ID, etc...We have various ways we can communicate with others around the WORLD! Sometimes in relationships we come across folks who have detective skills of Sherlock Holmes! They may see who your friends are on Facebook, Myspace, etc...search for you on dating sites, go through your text messages, well you ge the picture. At what point is it outside the boundaries?