do you work in Pret a Manger?
Yeah... but can be good on your own too somehow... albeit in a different way.but then as rich said, dinner is the time for relaxing, playful creativity and experimentation in the kitchen. find an interesting recipe to try, or improvise one of your own. the day is done, you have time to ponder, explore. and it's satisfying to sit down at the table, gaze at the main and side dishes, and think "we just made this from scratch." appreciate what you've produced.
the shared experience of cooking/dinner for two might be a factor. when I was single, I'd cook maybe once on the weekend but otherwise it was the bare minimum of effort, a sandwich woofed down just to quell hunger. the shared experience of cooking and dining with someone changes the dynamic, infuses a social element.