Love across the waves

When human and mermaid fall inlove. They always meet every life time they have and always being a inlove with each other but they always have a sad ending. The fate always make them meet and fall inlove to each other and there's a guy named Selwyn lin who against their love stories he kept on hunting Aurelia bc he already know that she's a mermaid and want to use her for money.but why they always have sad ending? It's is because mermaid and humans are not meant to be? Even fate want them together their life was keep on repeating and having a sad ending untill They avoid having a sad ending and fight for their love and still wondering to have a happy ending.