Girl meets dog (spoilers)

Girl and dog bond
Girl and dog get blown up
Girl and dog part
Girl gets dog and they live happily ever after
This may be a case of me just not being in the right mood but I found this film very flat. We spend a lot of time watching Kate Mara being a mopey person and an exceptionally good supporting cast are given little or nothing to do. The scenes at war are strongly done but little else seems to work in this film.