Her name has been said so many times by so many people in so many different ways– adoring, hateful, protective, apathetic– that she can't even count them.
But not here. Here, she is nothing. Here, Rose Tyler doesn't exist; the closest thing to Rose Tyler is a dog.
Jackie and Mickey have long since moved on, gotten on with their lives, found places for themselves, ensconced themselves firmly into their spots. But not her.
She's the one piece left over after the rest of the puzzle has been completed, the lost fragment from a different box.