Naruto might be angry at first. He is not one to take betrayal lightly.
Naruto would probably feel a mix of emotions. Hurt, because he thought he could trust Rias. Angry, as it's a betrayal. But he would also be strategic. He would use his skills as a ninja, like his stealth and combat abilities. He might try to gather information secretly about Rias' actions. He could also reach out to his friends in the Naruto world for advice or help, while at the same time trying to keep a low profile in the world where Rias is, in case she has more plans against him.
He could initially be in disbelief. But then, his determination would kick in. He would likely try to figure out a way to make things right or get revenge, depending on how the story is written. Naruto has a strong sense of justice, so he may also be interested in finding out the root cause of the betrayal to prevent it from happening to others.
Naruto would likely be extremely hurt at first. He values loyalty highly, and this betrayal would be a big blow to him. He might go into a state of shock and disbelief.
Naruto would likely be deeply hurt. He is a character who values friendship and loyalty highly. Being betrayed by someone he might have considered an ally like Rias would be a huge blow to his emotional state.
In this kind of fanfiction, Naruto might face a lot of challenges. Maybe Rias, for some reason, turns against Naruto. Naruto could find himself isolated and having to fight against Rias' forces. He would probably rely on his ninja skills and his strong will to survive.
In this kind of fanfiction, it might happen because of a misunderstanding. Maybe Rias is misled by false information about Naruto. For example, some villains could fabricate lies about Naruto's intentions or actions, causing Rias to believe he's a threat and thus betray him.
He might react with hostility. Dark Naruto has a certain edge to him, and if he sees Rias as a threat or someone he doesn't like, he'll likely oppose her. He could use his combat skills to challenge her directly.
Initially, Naruto would be heartbroken. His friends and his village mean everything to him, and the thought that the gods, who are supposed to be just, have turned against him would be a huge blow. However, he wouldn't give up. He would use his determination and his unwavering belief in himself. He might start looking for allies among those who are also disillusioned with the gods or who believe in his innocence.
At first, Naruto would be extremely hurt. He has always considered Team 7 as his family, so their betrayal would be a huge blow. He might go into a state of shock and disbelief.
He might be initially shocked and heartbroken. Naruto has always valued his friends and the village's trust, so when that's suddenly taken away, he's in disbelief. He could try to reason with his friends at first, but when they don't listen, he might become angry and determined to prove his innocence on his own.
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.
Naruto would be determined to get to the bottom of it. He would not just accept the betrayal at face value. He would use his skills and the help of his friends to investigate what made Jiraiya turn against him. Naruto's ninja way is about never giving up, and this situation would be no different. He would fight against this betrayal, both physically if Jiraiya became an enemy in combat, and emotionally, trying to understand the reasons behind it all while still holding on to the hope that Jiraiya could be redeemed.