The author is trying to teach us that your dreams can come true if you try hard enough but sometimes trying to hard can hurt you. For excample George and Lennie had a dream to have bunnies for Lennie to tend and George to take care of the farm. They where trying very hard for there dream to come true but threw the processes Lennie got shot.
"Because I got you. We got each other, that's what,that gives a hoot in hell about us."pg.104