Perhaps she has a new mission or calling that takes her away from Camelot. It could be something related to the greater magical world. For example, there could be an ancient magic that is in danger of being lost or misused, and she is the only one who can save it. Since Camelot has been rather unkind to magic in general, she might feel that she has to leave to fulfill this important task.
Long - term, Arthur may start to question his own beliefs. Merlin leaving could make him re - evaluate his stance on magic. If he realizes how much he has lost without Merlin, he might start to think that perhaps the way magic has been treated in Camelot is wrong. This could lead to a change in Camelot's laws regarding magic in the future, but it would be a slow and difficult process as he has to overcome his own prejudices and the long - held views of the court.
One possible reason could be ideological differences. Maybe she discovers some practices within the Order that go against her moral compass. For example, if the Order starts to use unethical magic in their fight against the dark forces, Hermione, with her strong sense of right and wrong, might not be able to tolerate it and decide to leave.
One reason could be that he feels ostracized. Despite his efforts to protect Konoha, some villagers still look at him with suspicion because of the Nine - Tails inside him. He might just get tired of constantly having to prove himself and decide to leave in search of a place where he can be accepted for who he is.
A plot might involve Merlin leaving Camelot to seek greater magic knowledge. He has learned a lot in Camelot, but there are still secrets about his powers and the old magic that he can't uncover there. So, he sets off into the unknown, leaving behind his friends and the life he has known. This could lead to him encountering new magical creatures and learning ancient spells that he can later use to help Camelot in a time of great need.
Gwen could also be a very sympathetic character. If Merlin leaves, she would be one of the few who truly understand how much he has done for Camelot. She has seen his selfless acts and his loyalty. She might be heartbroken that he has to leave and feel powerless to stop it. Also, she has to deal with the potential loss of a great ally in the court and a good friend. She might struggle with trying to convince Arthur to let Merlin stay or find a way to bring him back.
One possible reason could be to escape the danger in England. Given the dark forces that were at play, especially Voldemort's rise, they might have felt it was safer to leave. Another reason could be for a fresh start. Maybe they wanted to explore new magical cultures and communities in other parts of the world.
One possible reason could be a difference in ideology. Maybe Spider - Man has a more local - friendly approach to crime - fighting while the Avengers are often involved in large - scale, global threats. He might feel that his skills are better utilized in his own neighborhood, like Queens, rather than in the grand, often cosmos - level battles of the Avengers.
Perhaps they are forced to leave due to false accusations or being framed for something they didn't do. This could create a situation where they feel they have no choice but to leave Konoha in order to clear their names and also protect the village from the real threats that might be lurking in the shadows.
It might be due to a self - sacrificing decision on Harry's part. He could believe that by leaving, he would protect the Weasleys from the dark forces that are constantly after him. Since he has so many enemies, he might think that as long as he is around the Weasleys, they are in danger.
One possible reason could be a difference in ideology. Maybe Peter Parker feels that Stark's methods are too extreme or not in line with his own moral compass. For example, Stark might be involved in some projects that Peter doesn't agree with, such as using certain unethical technologies in the pursuit of justice.