Loneliness

lone•ly adj. (lone•lier, lone•li•est) 1 unhappy because you have no friends or people to talk to: She lives alone and often feels lonely. As I didn’t speak the language I grew lonelier and lonelier. 2 (of a situation or period of time) sad and spent alone: all those lonely nights at home watching TV 3 [only before noun] (of places) where only a few people ever come or visit isolated: a lonely beach note at alone
lone•li•ness noun [U]: a period of loneliness in his life


The one peculiar thing about loneliness is that, you don't have to be alone to be lonely.

Or is that just melancholy?