There’s a day when time finally runs out. When he sees how she’s going to end (and it’s all his fault), he thinks he’s going to be sick and if she’s goes, he might just go too, but then Pete appears from nowhere and saves her. He thinks seriously about letting go, but the hole closes before he can act on it. Walking away from that wall might have been the hardest thing he’s ever done.
He searches for months, speeding through the universe, faster than he’s ever gone. He drags himself around the ship unless he thinks he might be close, and then he leaps into frenzied action, turning and pulling and hammering at six controls at once. Each time that he’s wrong breaks him all over again, but he always sets new coordinates and tries again. He can’t stop, though every fibre of his ancient being knows that he should.
Then he does find it. He waits for agonizing hours, uncharacteristically biting his fingernails. He doesn’t tell her, when she finally gets there, that she’s used almost all of the time they might have had just travelling to Norway.
When he tells her that he can’t come through, that both universes would collapse, she says, “So?” and she’ll never know how close he comes to actually doing it, to punching his way through for the split second of bliss that would be her, warm in his arms, as two universes shattered and died around them.
And it’s she who says it first. She chokes on it, with tears and the strangeness of saying words for what they’ve known for so long now. He swallows, opens his mouth, feels the words pushing up from the buried places. “Rose Tyler…”
He can’t decide if it’s poetic irony or blatant injustice that the program ends before he can speak the words. He knows that Jackie is holding her while she sobs, a universe away. For once, there are tears on his own face.
Others ask about her. At least one tries to replace her, but no one ever gets close. He’s forgotten how long it takes to pretend that he's "over" a love.
The power of emotion never ceases to amaze him. Even as he jokes with other companions and saves another dozen planets before lunchtime, he regrets not telling her. Someday it will fade into the background, to be shelved with the hundreds of regrets accumulated in ten lifetimes; but right now it just hurts.
He gets along. He learns to enjoy life again, the way he does. He names Gallifrey to Donna and tells Martha what it looked like. He tells himself that someone needs to remember his home because eventually he won’t be able to, and Gallifrey deserves more than he can give.
The other reason is her, of course. In a year or two, she might have asked about Gallifrey and he would have told her. He tells the others in her honour, and while his eyes watch Martha soak in the details, his mind imagines Rose and the way she would have listened, the questions she would asked and the ones she wouldn’t have, the way she would have hugged him silently when his voice faltered.
Time goes by, and most of it is for her.