At first, he might try to hide his pain from their child. He would want to be strong for the child and not let the abandonment affect the child too much. But as time goes on, he may have to face his own emotions and deal with the situation more openly.
He could become very determined to find out why Sakura left and try to win her back. Naruto is known for his perseverance, and he wouldn't give up easily on his family. He might also start to question his own actions and wonder if he could have done something differently to prevent this.
Naruto would be devastated. He sees Kakashi as a mentor and father figure. He might initially go into denial, not believing that Kakashi would actually abandon him.
At first, Naruto is likely to be heartbroken. Konoha has been his home, and he has always longed for acceptance from the villagers. So being abandoned would be a huge blow to him.
On the other hand, it can also inspire new discussions and fan-made content. Fans might start creating their own versions of what could have happened instead, or write stories where Naruto tries to win Sakura back. It can also lead to in - depth analyses of the characters' relationships and personalities within the fanfiction community.
Naruto could also feel a deep sense of hurt. After all, he has been through a lot with Sakura. In the face of her betrayal, he might start to question his own judgment of people. However, being Naruto, he would not give up easily. He might try to find a way to redeem Sakura or at least make her see the error of her ways. He would draw on his own experiences of being ostracized in the past and use that to try to understand her actions and find a solution.
She might be heartbroken. Sakura could initially be in shock and then fall into a deep sadness. She may blame herself for Naruto's leaving, thinking that she could have done something differently.
However, in other cases, Naruto could be hesitant. He might have grown so used to their friendship that the idea of a romantic relationship with Sakura is a bit overwhelming. He could take a step back and say something like 'Sakura, this is really unexpected. I need some time to think about this.' This would then lead to a more complex exploration of their relationship in the fanfiction.
Naruto's reaction could be complex. Since he has his own feelings for Sakura, this situation could stir up a lot inside him. He might initially be a bit hesitant in how to approach her because he doesn't want to overstep any boundaries. But in the end, his natural instinct to help a friend would take over. He would listen attentively to Sakura, his eyes full of determination to make her feel better, and use his own unique way of thinking to give her advice or just be a shoulder to cry on.
He may also choose to defend himself without really fighting back. Naruto values Sakura as a friend and teammate, so he would be reluctant to harm her. He might just try to dodge her attacks and keep talking to her, hoping to snap her out of it.
Naruto could try to talk her out of it. He is a firm believer in the power of friendship and words. So, he would likely use his words to try and break whatever spell or wrong idea is in Sakura's head that made her want to kill him.
Maybe she has some unresolved issues from her past, like her unrequited love for Sasuke that still lingers in the back of her mind. This could make her question her relationship with Naruto and lead to her leaving.