She was too human. And that was why he loved her. How ironic it seems, now, that he can't love her anymore because he isn't human enough. Human is one of the few words with resonance. One simple word, just classifying a species, that has the power to define what he loved and the reason he can't any longer. Loving someone so much you hate them … he never thought paradoxes like that were possible.

The lack of words – sometimes that means more than saying them in the first place.

Run. Bananas. Gallifrey. Anagram. I love you.

Run. If you say this, you can make someone out of breath when they didn't want to do any exercise in the first place. But don't say it, and they could burn to death from the fire from which you're telling them to flee. Or the plastic models …

Bananas. Saying this can make you look insane, like a monkey. Not doing so, and a person won't get enough potassium, or on of their five-a-day. Which would be devastating.

Gallifrey. Not saying it makes no difference to anyone. Saying it makes someone want to know more. This gives you a reason to tell them about what you've lost. Which is probably better left unsaid …

Anagram. Letters in a different order, giving a word a new meaning. Silent becomes Listen. Live becomes Evil. This stresses the need for chronology, something he'll never want.

I love you. Said, they give you everything you want. Unsaid and you have to watch another man getting everything you want.

See, speaking is important. Which is why he's glad he's so talkative. Then why was he silent at the one moment he most needed to speak?

He hopes things work out all right. He wonders if they'll ever get married; have children; grow old together. How he will try and emulate their life from before. If they'll stay that way.

Because he can't imagine his double waking up one day and finding that he doesn't love Rose Tyler.

He hopes she won't wake up and find she doesn't love him.

He knows it's a possibility. He knows what she's like. Reckless. Unstable. Effervescent. Glorious. Infuriating. Courageous. She won't settle for something she finds inadequate – she's too bright to do that a second time. Knowing her, she'd push him away, adamant to blight what he's given her. Determined not to settle for something she wasn't even looking for in the first place. Too stubborn to accept that things are better this way, the other way from what she expected. They are.

Stubborn. That's another word that describes her. Compassionate, unwilling … But these don't mean anything, because they're just words. And she's so much more than that.

A pinprick of light in the dark blanket that has been the past nine hundred years. Radiance and gold and fire and a breath of fresh air. Yes – that describes her better. But not quite. Words strung together – they mean more than when they're alone, but they're just a cliché. A normal phrase, flung into everyday use so they don't mean anything anymore.

But he meant more when he wasn't alone.

He'll never mean as much again.