Here is the problem with the clone of the 10th Doctor and the implication that Rose going off with the clone is a happy ending: Doctor Who is a sci-fi show, and sci-fi has a fifty + history with the idea that a clone is not the same thing as it's progenitor. So basically, Rose gets something that looks like the Doctor and might act like him (sometimes) but isn't.

Additionally, there is this bullshit implication that the "real" doctor could never be happy in a relationship, IDEK.

For you: squee about Yuletide!