alone in the dark

Once a great man said 
"Language... has created the word 'loneliness' to express the pain of being alone. And it has created the word 'solitude' to express the glory of being alone"
But i'm keeping ask Why and when exactly we feel lonely, believe or not i realize that, feeling lonely depends on the one you are alone with..
You are no longer lonely .. because you like the person you are alone with. 
but feel so lonely .. because i hate the person i'm alone with.