After Nellie's dramatic explanation of why she didn't tell him his wife had lived, poor, miserable Sweeney decided that he needed someone to fill his empty heart, even if she was insane. They danced, sang, moved away, and lived happily in a sick, twisted way. Sweeney Todd was never the same, but he was a bit happier with Nellie by his side. They had two children, 2 dogs, and a cat. the whole family lived together until their children went to college. then, Nellie ans Sweeney died at the same age, 102.