Mr. Frank said, "We don't need the Nazis to destroy us, we're destroying ourselves." How were the people in hiding destroying themselves?

It was horribly hard to be cooped up in the annex for everyone, especially Anne. Anne had to share her bedroom, her desk, and her life with a stranger. She was constantly squabbling with her mother. Most of these squabbles were small, but she had nowhere to escape. There was little to no privacy for anyone and strict lights off and no talking hours had to be observed. No one could go outside and tension ran high when news of the war was not forthcoming. Besides all this, there were constant bombings and the fear of being discovered. Relationships broke down, but I would wager the Franks and the others in hiding did extremely well considering their situation. The annex became a microcosm of the outside world, mirroring those tensions and emotions others felt in the real world.