You've been with her for 10 or so years, I would safely assume there is something there that keeps you with her and I can tell that you do care about her but something concerns me about your post that I do not have the answer to but I would like you to ask yourself some things.

First off the entire original post seems to assume all of the change in the marriage is carried on the shoulders of your spouse. it assumes "she's changed" and that you're still the same loving husband you always have been. I am not here to point any fingers at you or fault either of you in any way but to say this. Rarely in a relationship does one person change without having been affected or affecting the other person along the way.

What I want to ask you is, if she is dealing with depression and weight, could there be, something you are overlooking that you might have a part in that has caused this rift between you that therefore also is causing her other problems? We as men are rarely as guilt free from things as we like to think. I know, I realize it may feel as though you are still doing the same things and only she's changed but if you look deeper into yourself can you find how you've changed too?

In every relationship it is always inefficient to try to* change things that we do not have any control of, and it seems to be an especially common thread throughout relationship forums of every kind. We men and women both tend to hit brick walls when we are looking at the other person and even if it is out of concern for health and well being, we try to figure out a way to fix, change or modify our loved ones. it never ever ever works. I realize that you've alluded to this idea in your OP but at the same time I think you've overlooked that nothing in your post has examined yourself and wondered "how have I changed also?"

It's something to ponder because this, my whole reply does not come entirely from thin air. my ex, who was overweight for many years, had her faults but hind sight many of the things she did, were partially from actions I may have taken or my inaction in certain areas. She was never in a bubble nor did all of her change come about free of mine. I did things also, that in time, caused her to be more apt to gain weight, not feeling cared for and loved. Did I think I was a caring husband? sure. was I faithful? of course. I was always there but being human I lacked certain areas where I needed to be something more than I was but in my denial of self examination I never realized those things.

I am NOT in any way saying you are entirely responsible for her state now, but it's worth looking at, and on top of that, always remember you can only control and change yourself. Perhaps in being able to step back away from the examining what's wrong with your wife, you can realize what is less than perfect in you and in changing those things, it may help to bring you both together again.