Ginny may have some insecurities. She might think that Harry doesn't see her in a romantic enough light, so she tries to force the issue of marriage. Also, the wizarding world might have some traditions or social norms that she misinterprets. For instance, if there's a belief that a certain age is the right time to get married, she could be pushing Harry because she thinks they're at that stage. Or maybe she's influenced by some of her friends or acquaintances who have gotten married, and she wants to be like them. But of course, forcing Harry is not the right way to go about it.
In the fanfiction, Harry might firmly reject Ginny's attempts. He could tell her that marriage should be based on mutual love and free will, not coercion. He may also distance himself from Ginny to make it clear that he won't be pushed into a relationship he doesn't want.
One possible reason could be that Harry is still haunted by his past traumas and feels he's not in the right mental state to marry anyone. His experiences with Voldemort and the losses he's endured might make him reluctant to bring Ginny into a potentially unstable future.
Maybe Harry has some unresolved issues from his past, like the trauma of losing his parents and many of his friends during the fight against Voldemort. These could make him hesitant to enter into a marriage with Ginny. He might also be worried about how the wizarding world would view their marriage, especially if there are still some who oppose him or his family.
One possible reason could be that she's had an argument with a friend at Hogwarts. Maybe she felt betrayed or misunderstood by someone she trusted. For example, if there were rumors spread about her, it could really hurt her feelings.
One possible reason could be that Harry might feel he's not ready for marriage. He has been through so much trauma from fighting Voldemort and might need more time to focus on himself and his own healing. Another reason could be that he might view Ginny more as a sister or a close friend at this point in the fanfiction, rather than a romantic partner.
Perhaps they have different ideas about the plot direction. Hermione, being the studious type, may want the fanfiction to follow a more logical and complex plot with Harry involved in solving mysteries or learning new magic. Ginny, on the other hand, might be more interested in a plot that showcases Harry's relationships, especially his relationship with her. So, this clash of interests could lead to a fight.
One reason could be that she has come to truly appreciate Zoro's loyalty. Throughout their adventures, Zoro has always been there for the crew, and Nami has noticed this. She might see him as a stable and trustworthy person to build a future with.
In the fanfiction world, miscommunication often plays a big role. Perhaps Harry was involved in some secret mission or task that he couldn't tell Ginny about right away. But Ginny, not knowing the real situation, might misinterpret his secrecy as cheating. For instance, he might be sneaking around to protect Ginny from a potential threat, but she doesn't see it that way.
Perhaps there is a political reason. Some powerful pure - blood families might be trying to strengthen their influence by uniting the Potter and Malfoy families through this marriage, even if it's by force. Another possibility is that there is a prophecy that they misinterpreted which led them to force this marriage.
One possible reason could be that Harry has been spending too much time on his heroic duties and not enough time with Ginny. Another might be that he made a decision without consulting her, like taking on a particularly dangerous mission. It could also be something as simple as he forgot an important date or anniversary.