George Gerbner first coined the term 'mean world syndrome' to describe how watching violent films on television skews our thinking, making us believe the world is a much nastier place than it is.
'Friendly world syndrome' is the opposite disorder. It is the result of all these exciting tweets and Facebook 'likes' about drunken nights out and parties attended. They give the impression that everyone is having a much better time than you are, and that they are far more popular.
As no one ever reports boring news (not even at the watercooler or in-house coffee bar), the net effect is that we feel our lives are dull and lonely in comparison. This leads to a general sense of isolation and despair. The answer is either: get a more exciting life, or just make one up, like everyone else does.