Woo, headcanons! Ok, so I have quite a few of these stored up, and I'll post some more as different chapters if people like this. So tell me what you think! :)
Disclaimer: Any characters, places etc. associated with Doctor Who do not belong to me.
The Doctor gazed at Rose, who was standing a few metres away from him. The soft light of the TARDIS was illuminating her face, and he noticed how beautiful she looked. Suddenly, the memories of all the times he'd nearly lost her flooded into his mind; all the times he thought he'd broken his promise to Jackie. He remembered how he'd felt when he thought he had lost her to the Dalek in Van Statten's Museum... How it was all his fault, she was dead because he brought her there and he didn't save her; but really, in the end, he did. He remembered when they were stranded in Sanctuary Base 6... That time had been different, because they were both alive, and they were together. He thought of how Rose had brought up living together, and how he didn't know what to say.
The most painful part was that he knew they couldn't stay together. Not for ever. He knew that eventually they would have to part, for her own good. He loved her, but one day, he would have to let her go.
Rose noticed the Doctor looking at her.
"What is it, Doctor?" she asked.
"I..." The Doctor was caught off guard. He looked into her eyes and felt a wave of sadness at the thought of leaving her.
"Rose Tyler," he whispered. Rose looked back at him, waiting for him to continue.
"You are beautiful," he said simply.