I can't imagine anyone would be happy in this marriage.
Your wife must be depressed and overwhelmed.
It sounds like there is such a deep hole she can't even think about climbing out.
It's easier for most to accept their current situation then to put forth the effort to change it.
I wonder if in her world/mind she thinks someday this will change, of course, someday never comes without effort.
All of the lifestyle conditions you have described could be causing depression.
Please keep in mind, your wife did not become depressed and overwhelmed over night, it was a gradual process... the process of healing will not come overnight. Start with the small things: encourage her to help you clean the house, then keep it clean- disorder is surprisingly depressing for most of us. With more energy will come more exercise and hopefully your wife will get back in shape- emotionally and physically.