Sure, fine. The Doctor believes in miracles and looooove. Who cares about factual inquiry when you've got boys kissing girls and having no personalities between them. Here's an engagement ring so you can propose marriage to a woman who has literally never met you... Before she blows one of those soldiers. Hurry!
The TARDIS chills out long enough for River to step outside, and while she's gone that voice comes back -- Silence will fall -- and the console screen Cracks, and we realize we're at Amy's house in Leadworth, the night before the wedding. River notes burn patterns on the grass outside, and the door is off its hinges, and it's verrrry creepy. Upstairs, in Amy's room, she's moderately appalled by the intense fetishistic collections of dolls and dioramas and stories and fantasies and whatnot -- "Oh, Doctor, why do I let you out?" -- and then she notices other things in the pile: The Story Of Roman Britain, a storybook version of the myth of Pandora.
It's scary, scarier for River because she's figured it out and maybe we haven't yet, but Stonehenge is a real place and this time is a real time, so maybe Amy's like a memory magnet pulling these things into alignment, except then you've got the Pandorica, of which the Doctor has remained steadfast about the existence until today, and who knows what else. So then is Amy creating these things out of thin air? Are we in the Matrix? Whatever it is, River is right to be scared.
Rory comes out to see if Amy's okay, and gets all territorial about the fact that one of the Romans gave her a blanket, and she is put off by the weirdness, but something about him -- something sad, weary --- makes her ask his name, about which she laughs: "It's just not what you expect Romans to be called. What's it short for, Roranicus?"
She doesn't know it but she's crying.
River calls the Doctor and -- don't ever do this, it's terrifying when you do this -- tells him not to raise his voice or look alarmed: Just listen. And the music -- and maybe that parallel act earlier, with the horseback riding -- lets you know these two things, River and the Doctor inside, Amy and Rory inside, are about to become one thing. And it's shivery, and it's sad, and it's scary, and it's plotted out so well that your growing sense of dread outpaces the growing sense of dread for everybody else, even scared-to-death River and worked-to-death Doctor, because you can see it lining up, and the ways it could be variously bad or sad or both or terrifyingly both.