I could maybe see using this type of thing if you and your GF were long-distance and you communicated better through email (although I will admit that if it were me, I'd read the first few paragraphs, think, "OMG, what is he getting at?" and skip ahead to the meat of the post). In conversation, we can plan it to death and it still will take that left turn in Albuquerque and leave us without "the script".
Having the nuggets you want to address, and bringing those up, then letting the conversation go where it may is probably your best bet. If you have trouble responding off the cuff, there's nothing wrong with saying that you have to process it and you can bring it back up later. Nothing says you have to wrap this up in one shot (and chances are you won't).