Man, I just want a poly ending. It's like, I don't mind a single couple at the end if it's set up to be clear that it's the winner, but there's always something deeply unsatisfying about setting up a perfectly balanced triangle drama with no clear winner or loser and then just having one person suddenly left out at the end. The author made it easy on themselves here because Ritsuka kind of lacks personality or will. Her entire character is just "I'm cute, I like this guy, I'mma cook for him" and there's absolutely no emotion or development beyond that, and then she just abandons the one motive she had at the drop of a hat at the end to make room for the brother. I also don't really like her and the friend together, since they're both super dull emotionless people. It'd be the most boring couple in the universe if they got together. He should get together with the other girl friend, they're a much better match.