They are very happy. I think it's safe to say that John has never experienced this kind of bone deep happiness before (as either John or the Doctor) and Rose thought she'd never feel it again. They have definitely become each others' universal center.

You know, I love mixing humor into the sexy. It makes it feel real, because sex can be so silly and funny in real life, so why should it be totally solemn in fic?

Try not to focus too hard on the change back. It's a long way from now and there's lots of plot and romance to come first.