Wow! I didn't expect so much advice. I apreciate it all, both positive and negative as I really have a lot going through my mind myself on this issue. I've probably thought just about everything that's been written, from "you should love her for herself" to "she's cheated me."
I don't know exactly how much she's gained but maybe these photos showing the change in her body will put it into perspective. Before:
After:
As you can see, the gain is substantial. To answer other questions: I do still love her as much as when we got married 9 years ago; I have gained about 20 pounds (it's hard not to with the huge amounts of food she prepares, desserts, etc.); there are no medical issues that I'm aware of and no kids; she readily admits that she loves to eat, and jokes about her plumpness as being the result of her happiness; she has gotten lazier about moving around as she has gotten bigger and doesn't like to walk for any significant distance. Does that help?