They could leave because of a prophecy. Some ancient prophecy might state that they need to leave Konoha to fulfill a greater destiny elsewhere. So they trust in this prophecy and leave their home.
Perhaps they leave to spread peace. They realize that Konoha, while a great village, is only one part of the world. They want to take their message of love and peace to other places. Naruto has always wanted to bring peace to the ninja world, and with Hinata by his side, they believe they can do more outside of Konoha. They could travel from village to village, helping those in need and showing that different villages can co - exist in harmony.
It would be a huge blow to Konoha. Naruto is a hero in the village, and his departure would leave a big leadership void. The villagers would also lose a great source of inspiration. Hinata is from a respected clan, and her leaving would also have an impact on the clan's standing in the village. Morale among the ninjas might drop as they see two important figures leave.
Economically, there could be some impact as well. Naruto and Hinata are popular figures, and their presence in Konoha likely contributed to the local economy in some ways, such as through tourism (people coming to see the famous Naruto). Their departure might cause a dip in certain sectors that relied on their popularity, but it could also open up opportunities for new shinobi to rise and bring in new sources of income for the village.
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.
Maybe they leave to find a better way to protect Konoha. They might think that by exploring the outside world, they can gain new knowledge and powers that will be useful for their village in the long run.
Kiba would probably be shocked. He's Naruto's friend and also has a connection to Hinata. He might try to convince them to stay, saying things like Konoha needs them. But once he realizes they are determined, he would support them in his own way, like promising to visit them. As for Lee, he would see it as a very brave decision. He would be inspired by their courage to step out of their comfort zone and start a new life elsewhere.
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.
Perhaps they are leaving together to search for a cure for some new and dangerous disease that has started to affect ninjas. They believe that by traveling the world, they will find rare herbs or meet wise sages who can help them develop a remedy. Naruto's determination and Hinata's knowledge of medicinal plants could be a great combination for this noble quest.
Some in the village would be sad to see them go. Naruto is a hero to many, and Hinata is also well - liked. People like Iruka would miss Naruto a great deal. But others might understand their need for a new life away from the village and support their decision.
Mentally, it could have a big impact on the other villagers. Their friends like Naruto and Sasuke would be affected. Naruto might feel like he failed to keep them in the village. It could also lower the morale of the younger generation who looked up to them as role models.
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.