Chapter 17: Why do you think Bruno has forgotten the names of two of his three friends back in Berlin? Why is the behavior similar to Gretel's focus on the map of Europe ?

Bruno no longer thought of those friends because he'd found new things and different ways to occupy his time.... Karl was obviously his closest friend.... the others were just children he played with. Gretel's focus on the map, newspapers, and movement of the war illustrated her new interests in the same way.