Personally every main character seems like they don't mind the world being destroyed. They are fighting for their own pleasure (Asuka), because its painful fate (Rei), and is an order (Shinji), not because they want to *save* the world. The world to them is a pain. So since it is gone, they don't have to suffer from the pain anymore. But the pain is a reminder that you're still alive. Since the pain is also gone, there is no meaning in their lives anymore. She's just feeling weary