He dreamed about her. He would be having a nightmare about the Bad Wolf incident but at the end Rose would say those words. And in another about Jenny, at her death. The face of Boe even said it, at the senate. It haunted him.
But no matter how hard he looked, he could not find her again. If she had shown up twice why not again, somewhere else? He had sulked in his tardis at first, just like Ten had done. But he hauled him self out of that place, it was Tens alone and he was better than that.
Run you clever boy, and remember. She hadn't finished that sentence. She was interrupted by her own death. Remember what? Remember her? He couldn't stop. He hadn't taken a companion on yet, it had been months. Sulking was Tens thing, he didn't need it.
He went to a playground and sat on a swing. A little girl came up and sat next to him she asked him why he was sad. He said he was looking for his friend this girl that he had lost twice. She gave him some advice on looking for things then went off to her mother. Little did he know that she was Clara. Little did she know, that he was the Doctor.
He resigned to being a monk. That is, until the phone rang and Clara found him again. He didn't get answers from her, but he got something much better, a companion and a friend.