The Doctor and Amy drag Vincent to the church, applying a little Bill & Ted logic to the situation, all about how since he painted the creature in the window of the church, let's go to the church. The Doctor is one Nervous Nellie today, and for once he'll tell you why: "The result of our trip could be the brutal murder of the greatest artist who ever lived. Half the pictures on the wall of the Musée d'Orsay will disappear. And it will be our fault."
But first, let's check in with Vincent's manic depression. Well, he's buried face-down in the bedclothes, so probably he's in a bad way. And yes, he is. And a very good actor is playing him, which means it's absolutely terrible. The Doctor offers to help, and he assures the Doctor that he cannot. "And when you leave -- and everyone always leaves -- I will be left once more with an empty heart, and no hope." The Doctor tells him there's always hope. "Your experience is incomplete," Vincent says darkly, before he begins to scream. "I know how it will end. And it will not end well."
The Doctor, this Eleven, he's capable of asking himself about things that the Doctor isn't usually capable of asking himself. Like, is this a good idea. He thinks not, and goes to fetch Amy. After all, Vincent asked him to leave. Everyone knows he's a delicate man. Just months from now he'll take his own life." Amy's not even trying to hear that, but the Doctor just says they're leaving van Gogh to take care of it. To get, note the wording, "to the church on time."
Of course, in the time it's taken the Doctor to get even more maudlin than his own self, Vincent has crested another wave, and he's ready to go. On the walk Amy expresses her sympathy for his sadness, but he's mature and self-aware about it in a way people on TV rarely are and people in real life invariably are: "Sometimes these moods torture me for weeks, for months. But I'm good now." Besides, if the tragic Amy Pond can soldier on, how can he not? He means it as flirtation, but since she doesn't know she's crying -- can't feel the tears pouring down her face -- she's just confused. "Oh, Amy. I hear the song of your sadness. You've lost someone, I think." There's a hole in her that she can't name. He understands. The monster you can't look at, brighter than the sun.