Why does Kahu cry during the movie?

One day during Kahu’s visit, Nanny tells Rawiri to look after the girl as she goes off to argue with Koro about his cold treatment. Rawiri decides to take her to the movies and sneaks her in under his leatherjacket. For most of the movie everything proceeded quite well according to Rawiri; however, the final scene was that of a wounded whale bleeding to death. The sounds of the death throes had apparently been recorded from real whales and this had an electrifying effect on Kahu. She could only weep and weep and nothing could cheer her up.