One possible reason could be their different career paths. Harry might be more focused on Auror work which is dangerous, and Hermione, being the practical person she is, may not want to live in constant fear for his safety. Another reason could be a growing apart in their values. Maybe as they get older, Hermione realizes that Harry has a more impulsive nature when it comes to making decisions regarding the wizarding world's politics, while she prefers a more calculated approach.
There's also 'Fractured Bonds' which is quite interesting. In this fanfiction, the break - up is caused by a misunderstanding that gets blown out of proportion. It shows how pride and miscommunication can lead to the end of a relationship. Hermione is heartbroken and Harry realizes his mistake too late. It's a really engaging read if you like exploring complex relationship dynamics.
Some in the wizarding community might be shocked. Harry is a hero, and they expected him and Hermione to be together forever. There could be a lot of gossip and speculation. People might take sides, with some blaming Hermione for breaking Harry's heart.
Well, Harry might feel really torn. He's best friends with both of them. At first, he might try to stay neutral, but it could be difficult. If he sides with Ron, Hermione could be hurt, and vice versa. Maybe he tries to mediate at first, but if the break - up is really bitter, he may have to choose who to be closer to, which would be a really tough decision for him.
She might be heartbroken at first. Hermione is someone who invests deeply in her relationships. She would likely retreat into her studies as a way to cope, burying herself in books to try and forget the pain.
Maybe it's because of their different outlooks on life in the wizarding world. Hermione is very much about following the rules and using magic for good and knowledge, while Draco has been more influenced by the power - hungry and sometimes underhanded ways of his family. This could lead to constant arguments and ultimately a break - up.
In the fanfiction, perhaps there are trust issues. Ron has a bit of a jealous streak. If he wrongly accuses Hermione of being too friendly with other male characters, like Harry or some new acquaintance, it could create a rift. This constant suspicion would wear Hermione down, and she might decide she's had enough.
One possible reason could be miscommunication. Maybe they didn't understand each other's feelings and needs clearly. For example, Harry's preoccupation with his fight against Voldemort might have made Cho feel neglected.
In some Dramione fanfictions, Ron might break up with Hermione because he feels overshadowed by her intelligence. He could be tired of always being in her shadow and decides to end the relationship. This then paves the way for a potential Dramione relationship as Hermione and Draco start to interact more.
Harry might be initially shocked and angry. After all, his wand is an important part of his identity as a wizard. He could lash out at Hermione immediately, demanding an explanation for her actions.