For some people, like my husband, "leftovers" were half-portions of something that got stuck in the fridge, not properly wrapped or covered, and forgotten about. When you pulled them out to eat them, they were dried out (or soggy, or slimy), cold, greasy, stale, or smelly. You held your nose and ate them anyway, but were still hungry. If they were really old or smelly, they could make you gag.
If that's your only experience of leftovers, it's hard to realize that properly prepared and stored food can be just as delicious as it was when freshly cooked. Happily, my husband has no problem eating frozen-and-reheated home-cooked meals and even does some batch cooking himself. I still can't get him to make extras of stuff to eat later in the week, though. Whatever is made for dinner, you eat it all or throw it out.
I don't like to eat the same main dish all week. If I make a big pot of lentils, the leftovers get frozen for future dinners. Sides/salads/accompaniments are great, though, like roasted vegs, slaw, potatoes, and so on.