First of all, you need to communicate with your wife and let her know your feelings and concerns. You can tell her that you are grateful to your mother for cooking for you, but you also hope that she can help share some work. You can try to discuss with your wife to see if she is willing to help with some simple preparations, such as cutting vegetables and washing dishes.

Secondly, you can try to assign some tasks to your wife, such as making her responsible for buying ingredients and preparing drinks and tableware. These jobs can help reduce the burden on the mother and make the wife understand the hardship and necessity of cooking.

Finally, you can try to cultivate your wife's cooking ability in your daily life. You can teach her some simple recipes or invite her to cook with you. This will not only increase the interaction and tacit understanding between you, but also let your wife know more about the cooking process and skills.