Rose really thought that the Doctor would tell her that he loves her. She thought he would tell her after the Slitheen.
I can save the world but lose you.
Say it, she silently pushed him. Say it.
He didn't.
Rose dismissed it. After all, they had all the time in the world.
She had thought he would say it after Reinette, but he didn't.
She had thought, after Mickey left, just maybe he would tell her.
He didn't.
But that was okay, because they had all the time in the world. They had enough time for her to love him, and for him to tell her he loved her.
All the time in the world.
Where did it go? Did it escape among the many days of laughter, of happiness?
So many memories, the end of the world, the Gelth, New Earth, 1941.
She hadn't felt the slow passage of time, the minutes that had crept by unnoticed while Rose laughed with her Doctor.
I love you.
How many time had those words ran through her head when she was with him, wishing, hoping.
All the time in the world.
The Doctor was a Time Lord, she reasoned, so he did have the time to tell her. But he didn't, so doubt crept in.
She had thought that he had loved her, but maybe not. Maybe she was just like any other companion, and when she was too old she would be kicked off and forgotten.
He was going to say it. Those three words.
"Rose Tyler, I-"
All the time in the world.
Maybe not.