Thr fact that they remained a tragedy, sua was the mermaid,uihyeon was the prince who is saved but the other princess was HIS HOMELAND, I loved how it incorporated the concept of the prince choosing the other princess over the mermaid by showing how uihyeon didi abandon his role as a freedom fighter and was willing to let sua go to save her from the harm of it all, even if his intentions to do all that came from his love for sua and to protect her from the chaos of the war, ultimately he chose to stay behind and do his part as a member of resistance rather than run away to a safe place with sua, this implemented the idea of him choosing his homeland as a patriot instead of settling down away from the war with the woman he loved, so he ended up choosing the "other princess" rather than the "mermaid" in the end 🤧