This has got to be one of the best relationship stories I have read in the HP universe. It wasn't about all looking pretty, talking sweetly and getting sweaty, it was about two characters with somewhat unique perspectives on relationships growing something that was truly good.
It's a nice change and it has given me much to think about in my own characterisations.
When I started reading this, I suspected this to be a ruse on Daphne's part (she is a Slytherin after all), but now I'm glad you didn't as I think it turned out much better this way.