They could leave Konoha in the fanfiction for a number of reasons. For example, Naruto might be disillusioned with the way the village is run. He has always fought for Konoha, but if he discovers some corruption or unfairness, he might decide to leave. Hinata, being in love with Naruto, would go with him. Another possibility is that they are on a mission that requires them to be away from Konoha for an extended period of time, and during that time, they realize that they like the freedom of being outside the village and choose not to return.
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 to seek a new life away from the political drama in Konoha. Naruto has always been in the spotlight and has faced many political challenges. Hinata, being by his side, might support his decision to leave for a quieter place. Maybe they want to raise their family in a more peaceful environment, away from the constant threat of enemies targeting Konoha.
She might be pressured by some powerful and malicious individuals within Konoha, and to keep her baby safe from their influence, she leaves. For example, if there are those who want to use her child for their own gain.
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 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.
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 reason could be that he feels betrayed in Konoha. Maybe some secrets were uncovered about the village's past actions towards him or his family that made him lose faith. So, he decides to start anew in Kiri where he hopes to find a different kind of acceptance.
Another possibility is that they leave because of a sense of disillusionment. They could have witnessed some corruption or unfairness within Konoha's leadership or among the ninja community. This makes them lose faith in the village and decide to start anew elsewhere.
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.