Okay but you can not deny that Rose had a special relationship with the Doctor, one that was different and so much more important than any of the New Who companions. Yes, they were all important and special in their own way, but Rose was something so, so different. She was there for him when he came back from one of the most horrifying experiences of his long long life. She made him smile again. She made him happy. She made him want to save the world, even when he didn’t want to himself. And that is so important and it lives on with him even when she’s gone and he’s changed again and again. He still remembers Rose and how she made him feel, how she brought him back from those dark places time and time again. And maybe it had nothing to do with Rose herself. Maybe it was because she happened to come around at the right time, a coincidence. But maybe, just maybe, the universe knew that Rose Tyler was exactly what the Doctor needed most at that time. His Rose.