Maybe Naruto gives up on Sakura when he discovers that their values and life goals are too different. Naruto is always aiming for the greater good of the village and to protect everyone, while Sakura might be more focused on her personal relationships, especially with Sasuke. This divergence in their priorities could lead Naruto to give up on her.
It could be that Naruto experiences a significant event that changes his perspective on love. For example, he might face a near - death situation where he has an epiphany about how he has been wasting his time on someone who doesn't reciprocate his feelings. He then decides to let go of Sakura and look for a more fulfilling and mutual relationship elsewhere.
One possible reason could be that Naruto realizes Sakura's true feelings for Sasuke are unwavering. After many attempts to win her heart, he might come to the conclusion that he's just chasing after someone who will never love him back. So, he decides to give up and focus on other aspects of his life, like his ninja duties or his friendships with other people in the village.
Maybe Naruto gets tired of always chasing after Sasuke. He has his own life and dreams too. He might think that he has sacrificed enough of his time and energy on Sasuke, and it's time to focus on himself and the village. He could start to believe that Sasuke has made his own choices and he can't keep forcing Sasuke to come back.
Another factor could be the nature of his ninja life. It's full of uncertainties and risks. He may worry that if he falls in love, his loved one could become a target for his enemies. Naruto has made many enemies over the years, and he wouldn't want to put someone he loves in danger, so he decides to give up on love.
It could also be due to a misunderstanding. Some false information might have spread in the fanfic's world, making Naruto believe that everyone has turned their backs on him. Like, some bad guys framed his friends, and Naruto, being unable to see through the lies at first, gives up on everyone in despair.
Naruto's decision could potentially strain his relationship with Sakura herself at first. She might be used to Naruto's pursuit and his sudden giving up could make her feel a bit lost or even angry. However, in the long run, it could also lead to a more honest and healthy friendship between them as they both learn to respect each other's boundaries and feelings more clearly.
One possible reason could be that Naruto realizes their goals and values are too different. Naruto is highly focused on protecting the village and achieving peace on a large scale, while Sakura might be more concerned with her medical career and the well - being of a smaller circle. Another reason could be the presence of Hinata. Naruto might gradually develop deeper feelings for Hinata which could lead to the break - up with Sakura.
One reason could be the sacrifices he has to make for the village. Naruto is so dedicated to protecting Konoha that he might feel he doesn't have time for love. His responsibilities as Hokage are immense, and he has to constantly be on guard against threats. Another reason could be past traumas. He has lost many people he cared about, like Jiraiya. This could make him afraid of getting close to someone again and losing them, so he gives up on love.
One reason could be exhaustion. Naruto has been through a lot in the original story. In a fanfic, if he is continuously put through more and more difficult situations without proper breaks, he might just give up out of sheer tiredness.
One possible reason could be that Sakura realizes Sasuke is too consumed by his revenge and she can't keep waiting for him to change. She might see that he is constantly putting her in a secondary position and she decides she deserves better. For example, Sasuke has left the village multiple times, leaving Sakura heartbroken each time.
It could also be that he is tired of the false expectations created by fanfiction. In fanfiction, his character might be portrayed in ways that don't match who he really is. He wants to be true to himself and his ninja way, so he gives up fanfiction.
Well, it might be that the fanfiction focuses too much on Sakura in a way that Naruto feels is unfair to the other characters. Naruto is part of a big world with many important people, and if the fanfic just hones in on Sakura all the time, he could get fed up. Also, if the fanfiction has Sakura constantly putting Naruto down or not appreciating his efforts like in the real story, that could be a reason.