I don't know why he doesn't have her make him a bento every day. I've been someone whose the "stay at home" partner (economic downturn, jobless but was looking) and there's only so much cleaning and laundry you can do. Theres SO much extra time in the day. I learned cooking out of wanting to help but it turned into a hobby out of pure boredom and being able to feel proud I contributed more. Plus homemade lunches are cheaper and save money. Not letting her make bentos is like... hiring someone then telling them to do nothing in an office where everyone else works hard. You feel bad and it's really boring cuz you have time to contribute and you want to pull your weight but your boss says no.
Also he needs to teach her a work ethic rather than being spoiled so if anything he should make her work 8 hours worth of chores a day or at least 4 (2 cleaning, 2 food) and 4 for home study.