One reason could be that in certain fanfiction scenarios, Harry sees Ginny more as a sister - like figure. He has grown up with her in the wizarding world, and their relationship has been so intertwined with friendship that he can't envision a romantic or marital relationship with her. It's like his feelings for her are more platonic in nature and the idea of marriage seems too far - fetched for him.
In some fanfictions, Harry might not want to marry Ginny because he may still be haunted by his past traumas. For example, his experiences with Voldemort could have left him feeling that he doesn't want to put Ginny in any more danger. He might think that his enemies could target her because of their relationship. Also, he could be focused on his own personal growth and self - discovery, believing that marriage at that time would hold him back from exploring his identity further.
A possible plotline could be that Harry decides to break off his relationship with Ginny before any talk of marriage. This causes a rift in their friend group, with some taking Harry's side and others Ginny's. Another plotline might involve Ginny trying to change Harry's mind by showing him how they could have a great future together, but Harry remains steadfast in his decision not to marry her due to his own insecurities.
In some fanfictions, Harry might not marry Ginny because the author wants to explore alternative storylines. Maybe they want to pair Harry with someone else to create new romantic dynamics. For example, they could pair Harry with a new character to show how his character develops in a different relationship.
Well, in some fanfictions, the author might want to create an alternate scenario where Harry has different relationship dynamics. Maybe they want to explore other pairings for Harry and so they write him as not liking Ginny to deviate from the original storyline.
Harry Potter has his own moral compass. Ginny is an important person to him. The idea of slutty Ginny fanfiction is disrespectful to her character. Harry has seen Ginny grow and develop, and he knows her true self. He doesn't want her to be objectified in such a vulgar way in fan - made stories.
Maybe in the fanfiction, Harry has some bad experiences at Hogwarts before. For example, he might have been bullied by some students or had a really tough time with certain teachers. So he doesn't want to go back.
It could be that in this fanfiction, Harry has found a new place outside of Hogwarts that he feels more comfortable in. He might have made new friends or discovered new magic that he can't practice at Hogwarts, so he doesn't want to go there.
Maybe Harry is a pacifist in this fanfic. He could have moral objections to fighting, believing that there are better ways to resolve conflicts, such as through dialogue or negotiation.
Well, it could be that Ron has his own ideas about how Ginny and Harry's relationship should be. Fanfics often take creative liberties and might deviate from what he thinks is the 'right' way for them to be together. He might not like seeing their relationship twisted or fictionalized in ways he doesn't agree with.
Maybe she doesn't like the way some fanfiction writers portray their relationship. Fanfiction can often take characters in directions that are not in line with the original essence of the character.
Maybe he doesn't like the way his character is often misinterpreted or distorted in fanfiction. Some fanfictions might take his character in directions that he would find unacceptable or disrespectful.