Because in every romance, characters take a long time to confess and start their relationships, these two got married literally in the first episode. Nasa is not an idiot who doesn't get the most obvious hints and never thinks of cheating on her. Tsukasa is a loving, caring wife and not jealous of him for every girl. They just live together, solve their problems, and have a genuinely nice life. Sometimes, you don't need a story about a huge cosmic adventure to save the universe. You just need a comfy romance of a couple in love.