Perhaps they leave because they feel restricted in the village. They want to explore the world and grow as ninjas outside the boundaries and rules of the village. They might also want to learn from different ninja cultures and techniques that are not available in their own village.
He could feel a sense of guilt. Sasuke might think that his actions or their relationship issues pushed Naruto to leave. He may then set out to find Naruto, not only to bring him back but also to resolve their long - standing issues. For example, if there were unspoken words or unresolved fights between them, Sasuke would see this as an opportunity to set things right.
For their friends, it can be a huge shock. Naruto, for example, who has always been in the middle, trying to keep their relationship strong, might feel a sense of failure. Their other friends from the ninja teams might be divided in loyalty, some siding with Sasuke, some with Sakura. In the village, it could cause a scandal. The villagers might gossip and it could also affect the image of the Uchiha clan again, as Sasuke is part of it.
The villagers would likely be shocked. Naruto is a hero to many in Konoha, and Tsunade is the Hokage. Their sudden departure would cause a great deal of confusion and concern. Some might think that Konoha is in danger if two such important figures have left.
It could change the power dynamics in the Naruto universe. If Naruto leaves the village in a yaoi fanfic, his absence might create a power vacuum. Enemies could see it as an opportunity to attack Konoha. Also, his new relationship with another male character could lead to new alliances or rivalries between villages depending on how the other villages view their relationship.
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.
The exact timing of when the Swordsmith Village Arc begins in the manga is a bit tricky to pin down precisely. It could be different based on how it's distributed. Your best bet is to look for information on manga platforms or from fellow manga enthusiasts who are up-to-date on these things.
The Swordsmith Village Arc typically begins around a certain point in the manga series. However, the exact starting chapter can vary depending on different translations and editions. You could try looking up reviews or summaries to get a precise answer.