Make it clear that you cannot carry out the activity, rather than suggesting that it is a matter of convenience or choice that you don't carry it out, that being the case, where applicable.
e.g. Your wife doesn't cook for you because she likes to, or chooses to, or you prefer her to.
She cooks for you out of necessity, as your limitations mean that you cannot cook for yourself.
Give reasons why you cannot cook for yourself, etc, etc.
