I did something new here, and read a lot of the comments before responding, so really, a lot of the issues that sprang to my mind about the characters were covered early on. Though I would like to emphasize that you really nailed the characters' personalities, it really sounded like John in my head, especially.

As for being a female and not liking John in this? I think the story contains that. Elizabeth reads John like a book and turns him down. Rodney isn't expecting to ever be propositioned by John, so the thought that John is desperate in a "in two weeks we may die" doesn't fully get through to him.

But, finally, what struck me the most about this, was where it ended. I had printed the thing out to read while be dragged to random family event and I thought that I hadn't grabbed the last few pages by mistake! So this is my not-so-subtle hoping wishing-ness for a sequel.

Because sorting this out is going to take real skill on John's part.