Why has my wife stopped cooking food for me?
Solution 1:
You can only receive one home-cooked meal per day. Other than that, this appears to be a bug experienced by other players. The exact trigger does not seem to be known yet.
Solution 2:
If you have sold the home cooked meal then your wife will stop cooking for you. I verified it in game and it does happen to be the case.
Solution 3:
On both my first and second run my wife stopped cooking for me after I became a werewolf. Even after I cured this character she never did start cooking for me again.