The lack of communication can have a significant impact on their relationship. If not resolved, it could lead to a permanent rift. Sasuke might start to resent Sakura for not giving him a chance to explain or make things right. On the other hand, Sakura might find it hard to move on completely without some sort of closure. This situation can also affect their character development. Sasuke may become more brooding and withdrawn, while Sakura might become more independent but also a bit cold - hearted in the eyes of some characters. And it can change the overall direction of the fanfic, as their relationship is often a key aspect of many stories.
It could drive a wedge between their group of friends. If Sakura and Sasuke are part of a larger group, the others might be forced to take sides or try to mediate, which can cause a lot of tension within the group. Also, Sakura herself might start to feel isolated as she cuts off communication with Sasuke. She may miss out on important things related to Sasuke or the overall story arc that involves him.
Perhaps there was a miscommunication. Sasuke might have said something that Sakura misinterpreted. Let's say he was trying to be protective but came across as overbearing. Sakura, feeling her independence was being challenged, chose not to speak to him as a form of protest. And in the context of the fanfic, this miscommunication could have been magnified by other plot elements.
In a fanfiction where Sakura cheats on Sasuke with Naruto, there could be many consequences. Firstly, it would shatter the trust within Team 7. The camaraderie and unity that they had built over the years would be severely damaged. For Sakura, she might lose the respect of her friends and comrades. In the Naruto world, reputation is important. Naruto himself might be ostracized by some in the village who see him as a home - wrecker, despite his good intentions. And Sasuke could potentially go on a dark path again, seeking revenge or just distancing himself from everyone. Overall, it would create a lot of chaos and emotional upheaval.
In the fanfic, it might be because of a misunderstanding. For example, Sasuke could be wrongly accused of something, and Sakura, believing the false rumors, is so disappointed in him that she refuses to talk. Or perhaps Sasuke accidentally said something really offensive during an argument, which made Sakura so angry that she just cut off communication.
Sasuke could initially be a vampire who is full of anger and resentment, maybe because of how he was turned. But Sakura's positive attitude and kindness could start to soften him. He might start to open up about his past and his feelings. Sakura could develop from a somewhat naive vampire into a more worldly and wise one. She would learn about the darker side of the vampire world through Sasuke, and this would change her. Maybe she would become more cynical at first, but then find a balance between her old self and the new knowledge she has gained.
For Sakura, she could grow in terms of her leadership skills. If they encounter any difficulties in the forest like being chased by a group of wild animals or getting caught in a dangerous situation, she could step up and lead the way out. Sasuke might then realize that Sakura has the potential to be a great leader. And for Sasuke himself, he could become more open to the idea of a relationship with Sakura. The seclusion of the forest could provide the perfect backdrop for him to explore his feelings for her.
One possible plotline could be that after Sasuke has finally returned to the village and reconciled with Sakura, they start to rebuild their relationship. They go on dates, share their feelings and experiences during their time apart, and gradually their love deepens until they reach a point of expressing their physical love for each other.
There's also a possibility that their relationship could turn into a more complex, non - romantic one. They could become comrades who respect each other from a distance. Sakura could see Sasuke as a powerful ally for the village, and Sasuke could recognize Sakura's strength and importance. They may not have the close, personal relationship they once had, but they'll work together when necessary for the greater good.
It could be because of a dark power corrupting Sasuke. Maybe an ancient evil force takes over him and makes him see Sakura as an enemy. In some fanfics, this kind of external influence can completely change a character's actions. Also, it might be related to Sasuke's pursuit of power. If he believes Sakura is standing in the way of his ultimate power - seeking goal, he could be driven to kill her.
One possible reason could be Sasuke's focus on his revenge. His thirst for vengeance against Itachi might make him blind to Sakura's feelings and neglect her as he is constantly preoccupied with getting stronger to achieve his goal of revenge.
Maybe to explore different character arcs. The writer might want to see how Sakura would develop as a character if she strayed from her loyalty to Sasuke. It could also be a way to introduce new characters or relationships into the Naruto fanfic world.