A third element might be betrayal. If the person Park Hae In loved was unfaithful, it would surely make for a very sad love story. This kind of betrayal can shatter one's trust and love, leaving behind a lot of pain and heartbreak.
His on - screen presence plays a big role. Park Hae In has a charm that makes the audience care about his character. In a sad love story, we as the audience are invested in his character's journey of love and loss. We feel sympathy for him when his love is unfulfilled, and this emotional connection is what makes such a story appealing.
One possible reason could be distance. If they were separated by a large geographical distance, it might have made it difficult for their relationship to thrive and eventually led to sadness.
Maybe in a story, Park Hae In's character loves a woman who is already engaged to someone else. He has to watch from the sidelines as she prepares for her wedding to another man. He tries to suppress his feelings but every time he sees her, his heart aches. Eventually, he decides to leave the place to forget her, but the pain of unrequited love stays with him.
One key element is their unique personalities. Sung Jin Woo's strength and his journey of becoming more powerful, combined with Cha Hae In's own skills and determination, make for an interesting dynamic. Another element is the adventure aspect. They often go on adventures together, facing various monsters or challenges which further develops their relationship.
There's a fanfic called 'The Unseen Bond'. In this one, the author delves deep into the emotional connection between the two characters. It's not just about their relationship but also how their individual growth affects their bond. It has some really interesting character development for both Sung Jin Woo and Cha Hae In.
There could be a situation where Young was in love with Park Hae In but for some reasons like family opposition, differences in social status, or Park Hae In having feelings for someone else, the love story turned sad. For example, if Park Hae In was from a wealthy family and Young was not, the family might have tried to keep them apart, leading to a lot of pain and sorrow for both of them.
There could be a fanfiction where Park Jin Young travels back in time to his early days and has to relive his journey with new perspectives. This could include his struggles, his dreams, and how he overcame obstacles all over again. In this story, he might meet his past self and have some deep conversations.