In some fanfic storylines, there could be a misunderstanding. Sasuke might misinterpret Sakura's actions or words as a threat or betrayal. His ninja instincts kick in and he strikes her without thinking, only to realize later that he made a huge mistake.
Well, it could be due to his dark past. Sasuke has been through a lot and sometimes in fanfics, that pent - up anger and trauma might make him lash out at Sakura. He might see her as an easy target because she's so close to him.
In some fanfics, Sakura might avoid Sasuke because she's tired of his cold and distant attitude. She wants to surround herself with people who actually care about her and value her, so she chooses to stay away from Sasuke to find more positive relationships.
He might be jealous because he secretly loves her. He doesn't want to see her with other people.
A scenario could be that Sasuke blames Sakura for something that went wrong in his revenge plan. Maybe she unknowingly did something that set him back, and in his anger and single - minded focus on revenge, he starts to hate her. Another possibility is that in the fanfic world, there is a misunderstanding. Sakura is misinterpreted as being involved with someone who has wronged Sasuke, and this causes him to hate her without really knowing the truth.
Well, it could be that in certain fanfics, the writers want to create a more complex and angsty story. Sasuke's character is often seen as a brooding and driven one. So, they make him hate Sakura perhaps because they think it adds an interesting dynamic. For example, if Sakura is constantly trying to get close to him but he hates her, it can lead to a lot of conflict and emotional turmoil in the story.
Sakura's ability to forgive and still care for Sasuke despite his past actions could also make him proud. In many fanfictions, she represents unconditional love. This selfless love and her ability to see the good in him, even when he was at his worst, could make Sasuke proud of her as a person.
In the Naruto fandom, such a fanfic would be very out of character for both Naruto and Sasuke. They are comrades and friends with Sakura. However, some dark or AU (Alternate Universe) fanfics might explore extreme and unorthodox ideas. But in the main canon, they would never do this as they have a deep bond with Sakura. Naruto has been friends with her since childhood and Sasuke, despite his aloofness, also values her in his own way.
Another reaction could be that Sakura tries to follow Sasuke. She believes that she can change his mind or that she can be of help to him. She might leave her own responsibilities behind for a while to chase after him, thinking that their bond is strong enough to overcome whatever is making Sasuke leave.
Sakura would probably be initially very angry. She has strong feelings for Sasuke, but kidnapping is a very extreme act. So she would likely fight back, using her medical ninjutsu skills and combat abilities to try and escape.
Well, they might have simple daily routines like Sakura making breakfast while Sasuke trains outside. Then they could spend evenings together, maybe Sasuke teaching Sakura some new ninja techniques or just sitting and talking about their day.
In the fanfic, it could be that Sakura has her own reasons for not speaking to Sasuke. She might be trying to protect him in a strange way. She could think that by not speaking to him, she can keep him at a distance from some danger that she anticipates. It's a rather self - sacrificing act on her part.