Alternatively, Ginny could be very mature about it. She might respect Harry's decision, even though it hurts. She could choose to step back and give Harry the space he seems to need while secretly hoping that he will change his mind in the future.
One possible reason could be that Harry is too focused on his fight against Voldemort and doesn't want to put Ginny in danger. He might think that being with her would make her a target for his enemies.
In this kind of fanfiction, it could be that the author wants to explore a different dynamic. Hermione and Ron have a long - built relationship in the original series. Maybe the author feels that Ron and Hermione have a more 'grounded' connection compared to Harry and Hermione. It could also be about showing Ron's growth and how he becomes more worthy in Hermione's eyes over Harry.
One possible reason could be differences in their social status. In some fanfiction settings, Daphne might come from a pure - blood family with high - society expectations, and Harry, being an orphan with a somewhat 'outsider' status in the wizarding world, may not meet those expectations. Another reason could be conflicting personalities. Maybe Daphne is a very reserved and traditional person, while Harry is more impulsive and adventurous, which could lead to her rejection.
One possible reason could be that in the original 'Harry Potter' lore, Draco and Harry are from rival houses and have a history of animosity. So in fanfiction, Draco might reject Harry based on this pre - existing enmity. For example, Draco's pure - blood supremacist views might clash with Harry's more inclusive attitude.
Ginny might support Harry by simply being there for him. In the face of everyone else turning their backs, her presence can be a great comfort. For example, she could sit with him at meals when no one else will.
One possible reason could be miscommunication. Maybe Ginny feels neglected by Harry because he's so caught up in his own heroic deeds and doesn't pay enough attention to her. So she might seek comfort or excitement elsewhere.
Harry might be extremely hurt. He could initially feel a sense of shock and disbelief. After all, he may have started to develop some feelings of trust or kinship towards Severus. Then, he might turn to anger. Anger at being rejected, especially if he doesn't understand the reasons behind it. He could also feel a sense of loss, as if he has been deprived of a chance at a real family connection.
He may also get angry. Harry has a strong sense of justice and self - worth. Snape's rejection could be seen as unfair in his eyes, especially if he has started to develop some sort of positive feelings towards Snape. So, he might lash out at Snape or even try to prove him wrong by becoming more independent and successful on his own.