Why has my wife stopped cooking food for me?

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.

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.

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.