I feel like people are forgetting that this is sorta like two different timelines. Yes, the Ido and sejin of the first timeline did bad things to each other but this is a second timeline where the Ido and sejin got the memories of the first timeline couple as dreams, almost as if it was a gift from first timeline couple, so that they don't repeat the same mistakes. Second timeline Ido did nothing wrong and it feels wrong for him to be punished for first timeline Ido's mistakes.