Maybe Naruto tries to change himself completely in order to please Sakura. He could start training too hard, ignoring his own limits, and end up getting injured. This would not only make his physical state worse but also deepen his mental depression as he realizes that even his extreme efforts don't seem to matter to Sakura.
One possible storyline could be Naruto is depressed because he feels unappreciated in the village despite all his efforts. Sakura, realizing his state, tries to cheer him up by spending more time with him. They start training together and Sakura slowly helps Naruto see his own worth through her belief in him.
Well, one possible plot development could be that Naruto's hatred for Sakura creates a lot of tension in the story. Maybe it leads to some kind of rivalry where they constantly compete in missions or training. And Sakura's love could be unrequited at first, causing her to strive harder to prove herself to Naruto. Another development could be that the fanfiction explores the reasons behind Naruto's hatred, like some past misunderstandings that need to be resolved for them to have a normal relationship.
One possible plot development could be that Sakura's tears somehow give her a newfound strength or resolve. Maybe she decides to train harder to protect Naruto in the future. For example, she could seek out a powerful teacher or a hidden jutsu to become stronger.
Perhaps Sakura's injury makes her realize she has some hidden strength within her. She could start to have visions or gain new abilities while she's recovering from the stabbing. This could then lead to a whole new arc in the fanfiction where she has to learn to control these new powers.
For Naruto, he might develop better understanding of the girls' abilities. For example, he could learn more about Ino's mental communication skills and Sakura's growing medical and combat skills. This could make him more reliant on them in different situations.
For Naruto, he could develop more in terms of his leadership skills. In fanfiction, he might learn to be more diplomatic when dealing with the different clans in Konoha, especially when working with Hinata's Hyuga clan. He would become more of a unifying figure, not just a powerful ninja.
One possible plot development could be that Sakura struggles at first to master the Chidori. She might face setbacks and doubts from her peers, but she perseveres.
Perhaps Sakura gets into trouble during a training exercise and Itachi has to rescue her, which then leads to a more intense and focused training regime. Another development could be that Sakura starts to think like Itachi in battle situations, using his tactics to outwit her opponents. It could also be that as she gets stronger, other characters start to notice and either become jealous or try to recruit her for their own purposes.
Well, one possible plot development could be the reaction of their friends and family. For example, Sasuke might be shocked or angry as Sakura was his wife in the original storyline. And Hinata could be heartbroken as Naruto was her husband. Another aspect could be how Naruto and Sakura deal with the situation, whether they decide to raise the child together or face a lot of internal and external conflicts.
Perhaps Sakura uses her intelligence to outwit Kidomaru while in his armsgrip. She could trick him into loosening his grip by making him believe she has some valuable information or by creating a diversion. For example, she might pretend to be injured more severely than she actually is, causing Kidomaru to let his guard down slightly as he tries to assess the situation.