Part of sadness comes from feeling as if you are on the outside
  looking in, as if there is a great big party going on "somewhere
  else" but you're stuck where you are. But even at parties - how
  many people are really living in the moment and having a great
  time - and how many people are putting on the facade of having a
  good time? It's one of the reasons why celebrations often
  revolve around alco...hol, drugs, religion, a TV show, shopping,
  gossip, politics, or some kind of 'something' that takes you
  away from noticing that underlying sadness that you and all all
  people feel in their darkest moments - those moments of feeling
  disconnected from those around you."