Re: Constant Nagging
DD, it would be interesting to know where you live - are you in an eastern country or western?
In the east, many houses are built with the extended family in mind and so are at least somewhat easier to handle. In the west, houses are built with nuclear family in mind - mother, father and kids. So there are smaller rooms, less bathrooms etc.
In either case though, it sounds like your wife wants only nuclear family in her household and is taking frustration out on you. And not being understanding about things. Are your parents fit and active? Would they do well in their own place? Not that I'm suggesting you move them out but that may be on your wife's mind yeah? Would a "mother-daughter" type house be an option for you? I know its hard, esp these days in US to sell and buy a new house...but these mother-daughter houses have a separate living quarters and provide somewhat more privacy to both parent and couple.
You should maybe try to engage your wife in deeper discussion over the whole situation because when you discuss the little things she complains about, you really arent hitting the source of the problem I think. Theres something more on her mind than who eats what or who stays up late to watch tv. Talk it out and see what develops...
Best of luck, its not fun for you or for your wife I'm sure. Hopefully some good discussion will bring peace to your home.