You might try r/CookingForOne. I remember cookbooks for one or two.

There are just two of us. My approach is a combination of leftovers, repurposing (roast pork tenderloin > thin sliced for sandwiches > faux barbecue), and mostly scaling recipes.

Scaling is mostly arithmetic. Add some judgment - divide a 1/2 teaspoon by 6 and you have something not useful. You have to decide what to do. I would look at all the herbs and spices and decide what to do. Often the big deal is cookware. For casseroles ramekins help a lot - you still have to watch time and temperature while cooking as the surface to volume ratio goes up a lot.

When I was single working full time and in grad school in my 20s and 30s I took a different approach. I might make chicken one night, steamed broccoli the next, rice the next, then a big salad the next. It wasn't very interesting, but it was easy and I remain convinced that balancing meals over a week is as good as balancing them for every individual meal. *grin*