why did the shop fail after phoebe left

Staying at the House of the Seven Gables has taken a noticeable toll on Phoebe; although she is still as angelic as she was when she first arrived, Phoebe now has the marks of sadness and regret. Holgrave attempts to frame this change in her as a positive attribute that shows new maturity, but this cannot outweigh the feeling that life at the House of the Seven Gables has taken its toll upon her. THe positive energy that Phoebe emitted directly kept the positive energy of the store alive. With Phoebe gone there really was nothing positive and vibrant left in the house to sustain the store.