For anyone who loves the book and is wondering how they'll convey all the complexities and nuances of the relationships, the simple answer is that they won't. Despite it being in the title of the film, the bar and the men in it are barely used as a device to tell the story. They also clearly decided that Ben Affleck was to shiny to play uncle Charlie as-written, so they turned him into some kind of one dimensional knight in shining armour.
If you loved the book, go read it again and stay well clear of this nothing burger.