So, this is one of those niggling ideas that won't go away, even after you've slept on it. Basically, the idea stuck in my head for such a long time now is that the Doctor mindwipes Donna and dumps her back home, leaving her to get on with her old, boring life, but for some reason he can't seem to stay away; so he starts hanging around places he knows she might be – pub, supermarket, office, that kind of thing. But his superslickninja skills aren't up to much, and she soon catches on to him – only not; because she thinks this man is John Smith – the man who was at her house on that oh so weird day.
Either way, they start spending time together, having fun, just like old times (only without all the adventure and without Donna knowing the truth). Anyway, she starts having dreams about the man in the box, and starts to feel guilty because then she's not sure if her new found feeling for John are true or because he reminds her of the man in her dreams.
It’s just like Rio with Jem/Jerrica – only not. *shot*