Stay-at-home parent.
Or “domestic engineer” if you want to be fancy about it.
Fun fact I learned upon meeting with my financial advisor last week: It’s not uncommon for a married person with a high income to pay their stay-at-home spouse like an employee. There are possible tax benefits for doing it this way. Like, if you can get a tax write-off for “childcare expenses,” and your spouse is a stay-at-home parent, you can pay them like they are your employee, and write it off on your taxes.
Then, in turn, your “employee” could put 100% of their income into retirement, healthcare, and other tax write-offs.
The stay-at-home spouse could even form an LLC for this purpose.