One possible reason could be to search for a powerful artifact. In many fanfictions, there are often hidden and powerful items that can change the fate of a village or even the whole ninja world. Naruto and Tsunade might leave Konoha to find such an item before their enemies do. This would be a dangerous mission, so they keep it a secret from the rest of the village to avoid panic.
Maybe they leave because of a prophecy. A prophecy could have foretold that only they can prevent a great disaster outside of Konoha. So, they have to leave the village they love to fulfill this task. They are both strong and brave, and they would take on this responsibility without hesitation.
One possible reason could be to search for a powerful artifact. Maybe there's a rumor about an ancient item that can save the ninja world from a new, unknown threat. Naruto, with his adventurous spirit, convinces Tsunade to leave Konoha and embark on this quest.
One reason could be a mission. Maybe he gets a top - secret mission that requires him to leave the village under Tsunade's leadership without her direct involvement. So he has to leave without much notice.
Another reason might be that Naruto is seeking a greater purpose. In the fanfiction, his 'godlike' state could make him realize that there are threats out there that he can't face while being tied to Konoha. He may leave to protect the world on a larger scale, believing that he can be more effective away from the village.
One possible reason could be false accusations against him. Maybe he's wrongly blamed for a crime he didn't commit, like being framed for a major attack in the village. This would lead the village leaders to force him out to maintain 'peace' and security.
One reason could be to seek greater power. Maybe they feel that Konoha no longer offers the training or resources they need to reach their full potential. So they decide to leave and explore other places where they can become stronger.
One possible reason could be to seek a new life away from the politics and pressures of Konoha. Maybe they feel restricted by the village's rules and expectations. Another reason might be for a personal adventure. They could be in search of something that Konoha can't offer, like a new type of ninja training or a mysterious power source. Also, it could be related to protecting their family. If they sense some kind of threat to their family within Konoha, they might choose to leave to keep them safe.
One reason could be a special mission. For example, there might be a threat that only Naruto can help with in Suna. Maybe there's a new type of enemy that has some connection to Suna's unique chakra sources and Naruto's abilities are needed to figure it out.
Maybe they leave because of a conflict within Konoha. There could be political unrest or a group within the village that they don't agree with. They might think that leaving is the only way to avoid getting involved in something they don't believe in or to protect the village from the inside out in their own way.
One possible reason could be to seek new powers. Maybe they feel that Konoha no longer offers the kind of training or opportunities they need to grow stronger. Another reason might be to escape from certain politics or social pressures within the village. For example, Naruto has always been an outcast in some ways, and Ino might be tired of the family business or the way things are done in Konoha.
One possible reason could be a sense of disillusionment with the village. Maybe he feels unappreciated for all his efforts in protecting Konoha. Another reason might be that he is being framed for something bad in the village and decides to leave rather than face false accusations. Also, he could be lured by the promise of a greater adventure outside Konoha that is not directly related to money.