The Doctor could see her there. Dying. Bleeding and in pain and if the Doctor had been there, he could've stopped it. He could've. He should've.

And then, Jack's mind was gone.

"It's not you," he said, staying where he was, afraid that moving would break the dam he'd set up holding himself in. And he was doing so well, too.

"At least she wasn't alone," he said. "There's very little that's worse than dying alone."