He laughed softly, giving Jack a playful nudge with his shoulder. It was a relief to know that they were on the same page. He didn't know how he could have tried to explain what had happened to Jack, and who knew what sort of new issues a Jack from his future would have had.
As he mentioned Rose, the Doctor couldn't help but look away, pressing his lips together as if trying to stop himself from saying something. He nodded slowly and the dull ache he'd been feeling turned into a wave of agony. "Mmm, I took her back," he said softly. A small smile, albeit a rather sad one, played on his lips as Jack mentioned his clone. "Nah, I left him with Rose," he explained; he didn't add that he'd left them kissing on the beach, that he'd just walked away without saying goodbye, but the memory seemed to be burned into his mind. "She'll be fine. She'll be happy with him, take better care of him than I ever could," he nodded, swallowing back the lump that was forming in his throat.