Xander's reaction was actually one of the more helpful ones he could've had. Once he believed that Clark actually was Clark, he rolled with it easily, not geeking out or asking him stupid questions about the glasses that he doesn't wear (yet). So it wasn't nearly as bad as it could have been, and he's grateful for it.

And as he listens, one of the twisted knots of stress in his chest seems to loosen, knowing that she really did fall in love with him for him and not Superman. That she believes in him, not because of a comic book, but because she knows him. And that she has confidence that even if he doesn't grow into being that untouchable, pristine boy scout in a cape, that he'll become the best person he possibly can anyway, no more and no less.

He closes his eyes again, leaning his forehead against hers. "Thank you."