What is the loneliness?

I don't feel lonely when I'm all alone. I only feel lonely when I walk through a sea of people, but nobody sees me.

I don't feel lonely when there is nobody online. I only feel lonely when there are so many people online, but I don't know who I can talk to.

I don't feel lonely when I'm listening to a sorrowful melody. I only feel lonely when I'm listening to a funny song, but I just can't smile.

I don't feel lonely when I have something bad. I only feel lonely when I even have something good, but then I just can talk to myself.

I know my body is alive, but I have no idea about my soul.

I don't live, I just exist...