We (the two of us) do fine with 95% Costco shopping, and I have similar "she won't commit to eating something specific for a week" restrictions. The only real tricks are get better at storage[1], and get better at cooking[2]. FWIW, the 2% rebate on the executive membership always covers my membership renewal price plus $50-$100 off a shop.

[1] Yes, you need somewhere to stuff 24 rolls of paper towels etc. I ended up building more shelves in the voids at the top of closets and the like. Ladder-access only but it works out.

[2] Stop doing 32-ingredient cooks with baby bok choy and white tomatoes and whatever other exotic instagram reels crap. Buy beef, chicken, fish, then portion and freeze (a vacuum-sealer is not necessary but it helps). Buy a standard 4-5 vegetables and a couple fruits. Potatoes and rice for carbs. Then figure out a list of recipes you can make from those ingredients -- I promise they can be combined damn near indefinitely.