One reason could be differences in values. For instance, if Draco's mate has strong beliefs in equality and Draco has some traditional pure - blood supremacist ideas left from his family upbringing, this could lead to rejection.
External pressures could be another factor. If there are outside forces, like the expectations of their families or the wizarding community, that are putting strain on their relationship, it might cause the mate to reject Draco. For example, if their families are feuding, the mate may feel it's too difficult to be with Draco.
One possible reason could be a misunderstanding. Maybe Harry did something that was misinterpreted by his mate. For example, if he was seen talking to another character in a friendly way, his mate might have thought he was being unfaithful. Another reason could be differences in their long - term goals. If Harry's mate has a very different vision for their future, like wanting to live a quiet life while Harry is more adventurous, this could lead to rejection.
One possible reason could be their long - standing rivalry. Draco has been taught to dislike Harry from a young age due to their family differences. His pure - blood supremacist upbringing might make him reject Harry as a mate because Harry is seen as a 'Mudblood - lover' in the eyes of Draco's family and their circle. Another reason could be fear. Draco might be afraid of what the wizarding society would think if he accepted Harry as his mate. The wizarding world has its own set of norms and expectations, and a relationship between them would be highly unconventional and likely face a lot of opposition.
One possible reason could be some sort of external threat. Maybe there's a dark force that wants to use his mate against him, so to protect her, he's forced to reject her. For example, if there are dark wizards who plan to capture his mate and use her as a bait to get to Harry, he might think rejecting her would keep her out of danger.
One reason could be that it doesn't fit the original characterization. Spock knows Kirk in a certain way, and a pregnant Kirk in fanfiction might be a huge deviation from that. So he rejects it.
One reason could be love. Draco might have fallen deeply in love with Harry and his possessiveness is a way of showing his strong feelings. He doesn't want to lose Harry to anyone else.
Love. Just like any other character, Draco can be heartbroken in fanfiction. If he loses someone he loves, whether it's a friend or a romantic partner, he could cry. It shows his vulnerability and that he's not just the tough - guy Slytherin he often tries to be.
In many fanfictions, Draco could be injured during a duel. He is a Slytherin, and duels are common in the wizarding world. Maybe he underestimates his opponent and gets seriously hurt.
One reason could be the allure of the vampire - human relationship in both the Twilight and Vampire Chronicles universes. Writers might want to combine the two to see how Bella's experience with vampires like Edward in Twilight could translate to a relationship with Lestat.
It could be a way for fans to further explore the deep connection between Naruto and the Kyuubi. Since their bond is so strong in the original story, some might take it to an extreme with the'mate' concept, thinking about how their relationship could be on a more intimate level in a different, non - canon way.
One possible reason could be that in the fanfic, Hinata has different personal goals or ambitions that she feels would be compromised if she were to be with Naruto. For example, she might be more focused on her family duties or her own ninja training and career, and she believes that a relationship with Naruto would distract her from those things.