Because if I believe in one thing, just one thing, it's her...
The Doctor inhaled sharply and his eyes widened as he took in the sight before him. Door number eleven, and behind it, his biggest fear. There lay Rose Tyler, sobbing on the ground, much like how he left her on a beach so many years ago. Her skin was wrinkled and her hair was graying, but she still had fire in her eyes. It was then that she turned and unleashed her fire on him.
"Bad Wolf changed me, Doctor. I can never die. I'm thousands of years old, and all alone. I watched everyone I loved grow old and die while I was trapped here. We could've been together! The Doctor and Rose Tyler in the tardis as it should be! Why'd you leave me, Doctor? Why?" Her quiet anguish had turned into rage and she screamed at him with a fury and a volume that could've rivaled her mother's.
"I'm sorry! I thought it was best! I didn't know..." He couldn't bring himself to say the words out loud, but she heard.
"Liar! You knew! You always knew!"
"I only suspected! I had no way of knowing for sure!"
She laughed coldly at this.
"Oh Doctor. The woman you "loved" yet never had the courage to tell, living in perpetual hell because of you. I am your greatest fear!"
Her screams were high pitched and hysterical but he only replied in a quiet sigh, "Of course, who else?"
He stepped away from the room and close the door behind him, waiting for the gentle click then putting up a do not disturb sign. He wondered who he put it up for, the others or himself, as he walked down the hallway in silent despair.