I`m trying to find a movie about a boy who died and came back as a ghost and was friends with a living boy (who might have been his friend in life). I remember the living boy kept the ghost as a secret and would even let him stay in his room. At some point in the movie a girl found out about the ghost and kept the secret with them.
However, the ghost boy would often do strange or `bad` things and there might have been another ghost which was a girl, that he either did something bad to or something bad happened to her. I think that there was something that would happen to every ghost after a while and there was someplace that they had to go (maybe a sewer or tunnel) and at the end of the movie, the living boy and girl sent the boy ghost there and he was crying.
I think there was also something about an old abandoned house or shack.
I watched this movie sometime between 2008 and 2013 and I remember that it seemed very dark but I never really thought of it as a horror movie.