I've found with my ADHD friends, as well as my (autistic, bipolar, ?maybe adhd?) self, that "doing something for others" is somehow easier than doing it just for myself. That might put into perspective why it felt easier to make meals before a divorce. Feel like there's a way to hack that quirk, solo, but haven't figured it out exactly yet.
Coming a bit from the opposite angle-- I haven't eaten well for my entire life, and I'm trying to learn how to create a diet on my own, from scratch.
I rely on a lot of soup. Just cut veggies, freeze them. Dump them all in broth when I have energy. Spices are "whatever feels right." Cutting and cooking does not need to be on the same day. Very simple, gets me veggies, reliable. It's something to build from. Does not require much planning.