My husband is the one who has MS, not me, and shopping/cooking for the BBD can still be exhausting. I don't know if this will help, but here are some things I do...
1. I always shop at a store that is good at keeping things in stock, so I can shop from a list. There's another store closer, but trips there end up being a waste of my time. I also drive a little further to get to a store where I can buy almost everything I need, so I don't have to go to multiple stores. It required a few small sacrifices, but it was worth it. And I buy a few extra things off the internet, which are delivered right to my door.
2. I always shop from a list, and I organize the list into three colums, so I can put the foods down in an order that approximates my path through the grocery store. The first column is for fresh produce. The top half of the second column is for fish and stuff from the deli/seafood counter. The second half of the middle column is for stuff from the center aisles of the grocery store: oils, salad dressings, vitamins, whatever. The top of the last column is for meats. The middle of the last column is for dairy stuff (which my son and I use on occasion, even though my husband doesn't), and the bottom of the last column is for frozen foods. I keep my list on the kitchen counter, and I can add stuff to it through the week.
3. I make a menu for the week, and this helps me know what to put on the shopping list. It also keeps me from randomly poking around in the fridge trying to figure out what to make for dinner. I try to shop only once per week (which goes against my foodie tendencies, but it can work). At first it was more difficult for me, but I can choose a weekly menu in about 10 minutes now. I start with fish for the first two days after shopping (the day of and the day after), so I can buy fresh, wild-caught fish. The middle couple of days are bison, turkey, or chicken. The last couple of days I make something from pork tenderloin, frozen chicken thighs, or frozen shrimp.
4. I cook my meats in very large portions. I cook for dinner only, not breakfast, not lunch. I cook enough meat at dinner so that my husband and I can both put leftovers onto a salad for at least one day, often two days. This also means that if there's a night I just can't cook...we have leftovers in the fridge that are ready for my husband to eat.
5. We eat salad for lunch every day. Every day. I've worked at getting variety into the salads, but I stick with salads. After you eat salad for lunch every day for a while, it seems totally normal. I buy big tubs of pre-washed spinach and salad greens, and then I spend one day chopping stuff to go on top of it: scallions, bell peppers, red onion, button mushrooms. I store these in bags in the fridge, and then I just pull out handfuls of one thing or another to toss onto the salads. On each individual day, I may add other stuff to the salad: sliced avocado, chopped up clementines, sliced strawberries, a handful of whole grape tomatoes.
6. Everybody fends for themselves for breakfast. We bought a "Magic Bullet" for my husband to make smoothies in. It's easier to clean than a blender because the cups can just go right into the dishwasher. He uses a banana, a handful of frozen fruit, some rice milk, and a tablespoon of canola oil. Sometimes he'll reheat a bowl of leftover brown rice with a little rice milk and small amount of maple syrup. He doesn't vary this too much, either. As with the salads at lunch, eventually you get used to the same thing, and it seems fine. We leave variety to dinner time.
Good luck back on the diet.
My personal diet blog: http://multiplesclerosisrecipes.blogspot.com/