Under the sky

The story's main character is being shown to the reader as someone who is a bit unfamiliar with the unwritten rules of society evident when he thinks that everyone getting on and onto a train should use the open windows instead of the doors, it is also shown that he dose not live in that particular town but is very familiar with it. He also has an ego when comparing him self to others.
I really don't understand the last part of the story at all my only guess is that he regrets what he did.