Let's talk about the emotional stages of team 7 during part one and how they interact with one another
Naruto
The most important thing to understand about Naruto is that Naruto isn't a good person at the start. He's not generous, selfless, sweet, kind, or mature. He's not a hero or a savior. He wasn't born with a supernatural ability to love or anything like that. He's an emotionally-stunted, attention needy, immature child. He's still in the self-centered, or egocentric, stage of deveopment which makes him quite bratty. And all of this is realistic given what he had lived through; not trying to hate on him.
I hate when the fandom portrays him as a selfless, perfect, kind etc from the start. No, he grows to become these things by the end of part one. But part one is all about Naruto's growth to see beyond himself and to start to understand other people and the problems with the system, and within himself. Naruto too is part of the problem. His desire to become hokage is for entirely self centered reasons. This is normal given Naruto's age and the abuse he's gone through, however they are still things he must overcome if he is to become the heroic person he wants to be. Naruto's immaturity is acknowledged and discussed many times, and these are gradually overcome, yet in a way that allows Naruto to still retain aspects of that childishness that are good like his sense of hope and optimism. Naruto's extended childhood works in his favor as it gives him the time to change. And the biggest factor in changing Naruto and helping him let go of his immaturity and selfishness is Sasuke. In part, because of Sasuke's self sacrificial nature. And another part because of something I'll address in Sasuke's section.
Sakura
The reaction of Sakura and the other kids towards Naruto is also normal. Sakura on team 7 represents a normal child, not emotionally stunted or especially mature. As kids do at her age she sees the world in black and white and is all about following rules and obeying authority. Since Naruto doesn't follow the rules he is a "bad kid". It's just the kind of black and white, logical thinking kids go through. She shouldn't be demonized for doing the same stuff we all probably did. And she starts to change her thinking and to try to change her attitude as soon as she is called out for it by Sasuke. Sasuke also teaches her that it's good to break rules sometimes like when he ofers his food to Naruto and Sakura follows suite.
Sasuke
It's not a coincidence that Sasuke is the catalyst for both Naruto and Sakura to change. Emotionally he is the most complex of the three. By the time he joins team 7 he has trauma, cptsd, abandonment issues, survivors guilt, trust issues, has experienced tortuture while under forced helplessness, and has severe attachment issues. Let's not forget that he's being invisibly held hostage by the knowledge that his brother will come back for him someday. And he's burdened with the knowledge that the best way for him to get stronger to face Itachi (Sasuke's own personal satan) is to kill his closest friend. Or that even without Itachi's threat Sasuke is bound by duty to kill his brother. And if all this weren't enough Sasuke carries another burden, his other goal to to restore his clan's honor. As the last Uchiha Sasuke knows that all of his actions will be used by people, fair or not, to judge his family, a fact that is constantly thrown in his face. What a lot of people take as arrogance or pride, can be seen as his devotion to his family and his desperation to live up to/uphold his family's reputation.
Sasuke is bound by a lot of invisible pressures that have forced him to grow up way too fast, losing most of his childhood in the process. However in team 7 Sasuke at least has the chance to vicariously recapture a little of his childhood through Naruto and Sakura. That's why we get to see a childish side of Sasuke on team 7. Completely suppressed before, and disappears right after, the period of time while Sasuke is on team 7 is the golden age of Sasuke's life when he gets the chance to experience a part of childhood. Sakura, and especially Naruto, give that to Sasuke. But Sasuke's childhood ends for good when he leaves.
On the other side is Sasuke's maturity. Despite what the fandom may think, Sasuke displays a lot of emotionally mature behavior. He is able to empathize with and defend Naruto right after Naruto had just attacked him, even though he stood to gain nothing from doing so. His empathy with Naruto going hungry leads him to offer Naruto food, even at the risk of his own future, he recognized Sakura's feelings of self doubt before the chunin exams and addresses it quickly and subtly. When he thinks he's about to die he encourages Naruto to pursue his own dreams and make the most of his life. He tells Naruto to save Sakura while he sacrifices his life. He doesn't think twice to run to Naruto's rescue when he hears his brother is after him etc. All these are signs of maturity that can't be denied. So the question is,
what happened?
The problem is that though Sasuke often takes on the "adult" role, he's suppressing his own needs. Naruto can carry on and act childish and get the attention he desperately needs; meanwhile Sasuke gets overlooked. Naruto has a way of constantly making himself the center of attention. And this behsvior is completely understandable. Subconsciously Naruto is broadcasting his need for help, and he often gets it. And as someone with so little maturity people expect little to nothing from him. And this gives Naruto room to grow without pressure. But everyone just expects Sasuke to act like an adult and be strong. Whenever he doesn't instantly know what to do or shows weakness he gets attacked, not by enemies, but by allies. He is constantly put on a pedestal by Naruto and others. Sasuke has been taught, and it gets reinforced over and over, that human reactions or or any signs of weakness are not to be expressed. For example, Naruto despises sasuke for showing weakness to Orochimaru. Being afraid of Orochimaru doesn't fit into Naruto's mental representation of Sasuke and he doesn't really know how to handle it, even assuming Sasuke is an imposter. And this is when he calls him a "scaredy cat", which parallels what Sasuke has said to him before. It might seem on the surface to be the same, and Naruto sees it like that at the time, but there are major differences. During the demon brothers fight Naruto had frozen up and this makes him helpless. While it's the opposite against Orochimaru. Sasuke knows he is helpless and that terrifies him. It's not just a matter of overcoming his fear of a fight, or trying to react quickly, Sasuke has to overcome his fear of death. Sasuke also said what he did after the demon brothers were defeated, not while in the middle of a fight. Of course, goading Sasuke into fighting was the right move, as it is the thing that ultimately saves them, but it also raises the pressure on Sasuke and forces him to suppress even more of his humanity around Naruto, making him ultimately more vulnerable to the things that would come.
So after facing Oro he completes the rest of the 2nd exam handicapped with the curse eating away at his Chakra, defeats an opponent with no chakra and while suppressing another attack, has to face off against a clinically insane opponent who wants to quite literally bathe in his blood, finds out his teacher has been attacked and naruto is in danger from his brother, rushes to protect Naruto but is rendered completly helpless and is tortured/ taunted to the point of falling into a comma for weeks.
By this point Naruto has grown a little. He's been forced to see more of Sasuke's humanity and his childish view of Sasuke being invulnerable have shifted. But the damage from before has been done. Naruto isn't someone Sasuke can trust. When Sasuke challenges him to fight, for Naruto its a relief to get back their normal rivalry and a chance to prove himself to Sasuke, who he still admires more than anyone. But for Sasuke its not about Naruto, he's on the verge of losing all confidence and the will to fight, and he's desperate to prove himself to himself; he's fighting for his will to live. But inconclusive results, followed by an ill informed lecture from Kakashi that asks Sasuke to pick between his family and team 7, followed by the sound four who prove (again) that Konoha isn't strong enough to protect Sasuke or to give him the teaching he needs... and Sasuke's choice now seems inevitable.
The one who lost the most by leaving was Sasuke himself. Childhood, friends, people who care, the one he had fallen in love with, the best friend.... I think it's obvious he assumed Naruto and Sakura will move on without him. Sasuke put his life on the line for them on multiple occasions because he can't bear to lose anyone again, but he still keeps them at a safe distance because he knows the danger of relationships, meaning Sasuke's two strongest instincts after the massacre are diametrically opposed and in a constant war with one another. Lost in that war is any room to value himself. And because he values himself least, he doesn't understand what he meant to them, the impact he was having on them, and how much they cared for him too. So even as he's risking his life for them, even as his words and actions are changing them, he doesn't see his own significance to them.
Add to this how they can't understand him. He's been a child with a family like Sakura, and he's been isolated and alone like Naruto, so he has the ability to understand them. But neither of them have been through anything remotely similar to Sasuke. People still argue over who had it worse, Naruto or Sasuke, but the answer is obviously Sasuke. Sasuke experienced the same isolation and lonliness Naruto did as well as a million other things Naruto didn't. Naruto and Sakura can't understand betrayal by someone completely trusted. Or the pressure of being the last of his clan. They haven't ever experinced complete and total helplessness. Even Kakashi is ignorant and naive in how he addresses the issue. But Sasuke still had a huge impact on all of them that they can't forget. But while Naruto can't understand it completely, when he fights Sasuke he sees how much pain Sasuke is in. Pain that Naruto hasn't been able to accept perviously. And more than anyone Naruto recognizes his own culpability in pushing Sasuke to the point where he'd feel like going to Orochimaru was his only option. This is the second way Sasuke helps Naruto grow. Sasuke's humaness forces Naruto to let go of his pride. After all the times Naruto's immaturity had forced Sasuke to assume the mature position and suppress his needs, now their roles are reversed. Underneath it all Sasuke has been hurting, and damaged, and needed saving too. And Naruto failed him. Naruto finally doesn't despise him for it. He is finally able to accept the human side of Sasuke while still acknowledging him. And though Naruto fails to bring Sasuke back he does save him.
