Since it's a Naruto fanfiction, it might deal with themes of disillusionment. In the Naruto world, characters often face hardships and betrayals. The 'no longer in autumn' could symbolize a departure from a once - idyllic or nostalgic state. It could also touch on themes of self - discovery as the character's heart changes, perhaps realizing new aspects of themselves or their place in the Naruto world.
Without having read the 'a heart no longer in autumn fanfiction' in detail, it's hard to say exactly. However, it's common for there to be a character who is at the center of the emotional journey. This character might be someone who has been through a lot and is now trying to find themselves again. There could be family members as characters too, who either support or hinder their progress, and there may be a love interest that plays a crucial role in the character's transformation.
One possible reason could be a major ideological difference that has grown over time. Maybe Sasuke has adopted a more extreme view on protecting the village or avenging his clan that Naruto can't support. Another reason might be a misunderstanding that has festered. For example, if Sasuke was misinformed about Naruto's actions and intentions and has cut off ties because of it.
Well, it's a bit difficult to directly recommend similar fanfictions without having read 'A Heart No Longer in Autumn Naruto Fanfiction' in detail. However, you can explore the genre tags on fanfiction platforms. If it's a romantic Naruto fanfiction, look for other stories with the same or similar romantic pairings. If it has a certain plot element like time - travel or a particular character arc, search for fanfictions with those elements as well.
One possible plotline could be about the character's journey to rediscover their lost emotions. Maybe they start to open up after a series of encounters with different people in a small town.
Perhaps after facing too much betrayal from the village he loves. If the villagers turned on him despite all his efforts to protect them, it might lead him to close his heart in self - defense, not wanting to be hurt again. He's always tried so hard to gain their acceptance and if that was all for naught, it would be a huge blow.
One possible reason could be that he has become jaded after facing so many hardships in his life. He might have seen too much pain and loss, which has made him numb and less caring in the fictional scenarios of fanfiction.
It could be that the girl is someone Naruto has known for a long time, like a childhood acquaintance. She might have always been jealous of Naruto's growing popularity and power. So, she decides to play with his feelings. She pretends to love him and then dumps him publicly, making Naruto feel humiliated and heartbroken.
One possible theme could be redemption. If a character has a 'demon in his heart', they might strive to overcome it and find redemption. Another theme could be self - discovery. As the character battles their inner 'demon', they may learn more about themselves.
Another theme could be the end of something traditional, like the end of the traditional novel format as we know it. It could be an experimental piece that challenges the norms of writing and storytelling. The 'no longer a novel' part might suggest that it combines different literary forms, such as poetry and prose, to create a new kind of literary experience.
One possible cause could be over - exertion during a fight. Naruto is known for pushing himself to the limit. If he has been in a long and intense battle, it might put too much strain on his heart. Another cause could be some sort of poison or dark jutsu that specifically targets his heart function.