why does charlie have difficultly in conversations?

From the text:

"I started out the evening with every intention of being pleasant and making friends. But these days I have trouble getting through to people. I don't know if it's me or them, but any attempt at conversation usually fades away in a minute or two, and the barriers go up. Is it because they are afraid of me? Or is

it that deep down they don't care and feel the same about them?"