Outside, ready to go, fairytale completed, he tries to keep a little bounce in his step. River appears, grinning at him: "Did you dance? Well, you always dance at weddings, don't you?" There's something in him, all grown up like Amy, in a way, as he turns to meet his wife. "You tell me," he says, fully operating on her level for the first time. (Maybe this is when she falls in love: Transformed, finally; finally ready for the next thing. Or maybe the tux is throwing me off.)
"The writing's all back," he says, handing the diary over, "But I didn't peek." She thanks him; she means it. And when he gives her the vortex manipulator: "Are you married, River?" She is. She giggles at him. "No, hang on. Did you think I was asking you to marry me, or asking if you were married?" Yes. "No, but was that yes, or yes?" Yes, she says, as full of love and sadness as anything. Passionate, afraid, content, in love.
"River," he asks, leveling a look of just undeniable hotness at her: "Who are you?" He'll find out, soon enough. "And I'm sorry, but that's when everything changes." He grins, he heads inside, dancing across the TARDIS floor, toward the next adventure. Amy's sorted, Rory's sorted, River just got interesting and he restarted the universe. Not a bad day.
But before he can take off, the Ponds come roaring in. He apologizes, as though he's not skipping out on them, and they laugh at him. He points out that they still don't know what blew the TARDIS up, or why, on their wedding date. "And why now? The Silence, whatever it is, is still out there, and I have to..." He finally answers the ringing phone: "No, but that's not possible. She was sealed into the Seventh Obelisk. I was at the prayer meeting. Well, no, I get that it's important. An Egyptian goddess loose on the Orient Express. In space! Give us a mo."
He tells them goodbye, and they grin first at each other and then at him: "Goodbye," they say, to that old world, and shut the doors behind them. Neither is it a cage nor are they running away: This is the next thing.