There could be various reasons. Maybe the person Dumbledore wants for Harry doesn't have a good personality or they have different goals and values. Or it could be that Harry simply doesn't feel a connection with that person.
Harry might not marry who Dumbledore wants because of his strong sense of self. He wants to make his own decisions about love and marriage. Also, maybe he sees flaws in the proposed match that Dumbledore overlooks.
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, Harry might not trust Dumbledore because Dumbledore often keeps secrets. For example, he doesn't fully disclose the prophecy details at once. Harry could feel like he's being manipulated or not given all the information he needs to face the challenges. So, that lack of transparency can lead to Harry's distrust.
Maybe in some fanfictions, Dumbledore's character is portrayed in a way that Harry doesn't like. For example, if the author makes Dumbledore overly controlling or having some hidden motives that are against Harry's interests.
In some fanfiction, Harry might not trust Dumbledore because the author wants to explore different power dynamics. Maybe they show Dumbledore keeping too many secrets, like about Harry's past or the true nature of the threats he faces. This secrecy can make Harry feel manipulated and thus lead to a lack of trust.
In some fanfictions, there could be external forces that keep Harry and Ginny apart. For example, a powerful dark wizard might cast a spell that makes it impossible for them to be together romantically. Or the wizarding society in the fanfiction could have new rules or social norms that oppose their union, causing Harry not to marry Ginny.
Another possibility is that the antagonist is a powerful and ancient magical being that has its own agenda. This being doesn't want Harry to reach his full potential as Dumbledore hopes because it fears that a powerful Harry could disrupt the balance it has been maintaining in the magical world for centuries. So it tries to create obstacles for Dumbledore's efforts to help Harry.
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.
The person Dilareba wanted to marry the most was her father. In many documents, it was mentioned that Reba's face was full of happiness when he answered this question, and he said that the person he wanted to marry the most was his father. She believed that her father had no flaws in her heart. He was the perfect father in her dreams. Therefore, it could be concluded that the person Dilreba wanted to marry the most was her father.
One possible plot could be that Dumbledore wants Harry to take on a dangerous but crucial mission earlier than in the original story. He might be desperate because he sees a dark threat approaching faster and believes only Harry has the unique power to stop it.
One possible reason could be that Harry discovers some hidden actions of Dumbledore that seem manipulative. For example, if Dumbledore has been keeping secrets about Harry's past or his destiny without fully explaining them. Harry might feel used or deceived, leading to his distrust.