I'd recommend 'Forsaken Hearts'. In it, the hero has an intense love for a person outside the main romantic pairing, creating tension and drama throughout the story.
You might consider 'Wuthering Heights'. Heathcliff's love for Catherine is intense, but he also has an entanglement with Isabella. It's a classic with lots of drama and passion.
Well, one such novel could be 'The Secret Love Triangle'. In it, the hero has deep feelings for a woman who isn't the main heroine.
Well, it could be a new character introduced in the fanfic. Maybe a mysterious stranger who has some special charm that attracts Sakura.
One possible reason is a misunderstanding. The hero might think that they are in love with the person they marry, but later find out it was all a mistake. For instance, they might have misinterpreted their feelings of friendship or gratitude as love. Also, external threats could be a factor. If there is a threat to the hero's family or community, they might marry someone else as a way to protect them.
The hero might offer emotional support, like being a shoulder to cry on and providing words of encouragement.
The theme of acceptance is also prevalent. Juvia may have to accept her new feelings, even if they go against what others expect of her or what she expected of herself. And she also has to deal with the acceptance or rejection from the person she loves, which can be a very emotional journey in these fanfictions.
Well, it usually makes the story more complex. The hero marrying someone else could be a setup for a love triangle or a quadrangle even. It might introduce new conflicts, such as jealousy among the characters involved. Also, it can give the author a chance to explore different themes like loyalty and sacrifice. The other characters might have to decide whether to fight for their love or let it go gracefully.
The special part could be the unique way they meet and the challenges they overcome together. Maybe it's the depth of their emotions or the unexpected plot twists.
One 'juvia loves someone else fanfiction' I know is 'Juvia's New Love'. In this story, Juvia falls for a mysterious newcomer in the town. It shows a different side of her character as she struggles with her new feelings while still having memories of her past relationships. The story has some really interesting dialogues that make you feel for Juvia's conflict.
Well, it could have different effects. Sometimes it might push the heroine to fight for the hero's attention, or it could lead to misunderstandings that need to be resolved. It all depends on how the author handles it.