Feelings Of A Saddened Good Friend

You sit there next to them
They never smile, laugh or seem to be happy
Looking at you when you speak with a saddened look
Never knowing what's wrong
Whether they are feeling worse than they seem
Whether they are actually feeling better
Just looking, staring into space
No emotion except sadness
If you thought they were getting a slight bit happier
They go back down again and seem depressed
You try to make them happy but they shrug you off
That makes you feel they don't want sympathy
The look on their face tells a story
They are happy on the day of something good
Yet sad on a bad day, but what causes the sadness?
Feelings Of A Saddened Good Friend...