"Earlier." The Doctor looked over at Rose, his expression serious. "Was hard for me to let go, run away. After..." He shook his head. "Doesn't matter, now. 'S done."
He squeezed her hand, reminding himself that she was here, real and alive, and at least here, he could find her. That it didn't matter that his Rose was dead, so long as there was a Rose alive, somewhere. That there was a universe where she was still fantastic and alive and having an adventure - and it didn't matter if she was with him or not.
Or at least, that was what he was trying to convince himself of.