Okay, new theory on River Song -- that I totally believe that Rusty in his crack-tastic ways has either thought of in passing or was part of the why of the finale.
So, first of all, if she *is* his wife, it's not a romantic one, it's a necessary one for some crack-brained reason I have no desire to go into, but they are good friends, she's a semi-companion to him. And the reason that the Doctor goes through with his relationship with her despite knowing how it ends and all of the pain that will follow and thus somewhat plays her along is because he has to. He does what he does ... to save Donna. Because aside from loving Donna for her wonderful, amazing self, he knows that without Donna, he doesn't get to give Rose and a version of him a happy ending. Therefore, if he does marry River Song, he's playing her to a degree because he has to so he can have his happy ending with ... ROSE!!!!!!!!!!!! So, really? All about Rose.
And ... THAT at least makes sense with canon and consistent characterization, which is more than Moffat's work did and you know it's just the kind of crack that Rusty would adore. In fact, I bet Rusty set up the whole Donna being necessary to give the Doctor and Rose a happy ending because he saw River Song the same way. Yup, this is my new theory and I'm sticking with it.