I think she is making a good decision, I think two seasons was the right amount. I think doing X factor gave her good exposure and now it's time to move on.
Simon Cowell @SimonCowell 1h
She and I have had our ups and downs but now consider her a true friend. The door will always be open. And thank you Demi. Simon.x
Simon Cowell @SimonCowell 2h
To avoid speculation. Because of her tour next year it was unlikely she could do that and X factor.
So it was her decision...and I think, if the show will be there for a 5th season, she could return.