Their wedding. James's first reaction was to feel relief that he had been right-- that he had managed to find a truly happy memory, untainted by the war or the Lestranges-- and then, as he got swept up in the memory as well, he felt all the emotions of that day wash over him. It probably wasn't just a happy coincidence that this memory had been the first one he'd found, since it had been heavily discussed and he imagined that she must have been struggling to remember it. Ever since their very first conversation, when he'd been trying to prove that her marriage to Sirius was a fictional story.
My dad walked you down the aisle, and when I saw you -- well, I'm not sure what my face looked like, exactly, but I felt like the luckiest, happiest man in the world. That was what he had said, before. And now, seeing it through her memories, he knew exactly what his face had looked like. Hers, too, though that was something he'd never forgotten.
When the memory ended, he found himself back in his own mind, the connection broken. The warmth of the memory was still with him, but he was a little overwhelmed by it, by the reminder of what they'd been. He'd never gotten over that, although he had said he was going to try at one point; that was never going to be possible for him, not in the slightest. He still loved her exactly as she was now, and he had no doubts about whether she loved him, but he had still been stuck with that past, that planned future. She hadn't had any of that, until now, she'd just had the emotions from it, the love that had lingered even though she didn't remember how it had begun.
The most overwhelming part for him now was how much he wanted her memories to bring back that last, final part of their connection. He knew that he was loved, but he could not help the fact that he still, agonizingly, wanted to be remembered.
He didn't know how to express any of that, so for a moment he just smiled softly at Lily, swallowing down the lump in his throat. Then he said lightly, "I suppose it's too late to say I told you so."