Forgotten - S1.E36

The next day, the hospital venture involving Kendall is all gone, and now Donnie can't even remember Kendall. Stacey is mad, and talks to Kendall through the mirror, and Kendall tells her that it doesn't matter if she doesn't come back, she's happy where she is. Stacey doesn't buy that and tells Kendall she's in need of a sister. Kendall tells her it's over, and that she can't come back.