Loneliness
It strikes me that the world is full of lonely people. They do not act or look all that lonely on the outside, but their inner world is empty or near empty, and they know it. How is your heart? It is difficult to spot a lonely person...and perhaps it is difficult for the person to even recognize loneliness to be a problem that create difficulties for them. I think there are many indicators of loneliness. Maybe we should explore a little.