On a more personal level, they could face internal guilt. As Naruto grows up and achieves great things on his own despite their neglect, Minato and Kushina may realize what they've missed out on. This realization could cause them a great deal of internal turmoil and regret for not being there for their son when he needed them.
Minato would probably be very proud. He might notice Naruto's use of his own jutsu and be impressed by how Naruto has developed his skills. Kushina would be more emotional, maybe crying at the sight of Naruto growing up so well.
The significance could be that it represents a unique sad story in an English - related context. Maybe it's a story that stands out among others in terms of its sadness.
The phrase 'la triste historia in english the only story' is quite puzzling. 'La triste historia' is Spanish for 'the sad story'. The 'in english the only story' part seems out of place or perhaps it was an attempt to say that there is a sad story which is the only story when translated into English. It could be that there is a collection of stories in Spanish and this one sad story is the only one being considered for an English version or something along those lines. Without more information, it's difficult to be more precise.
Well, in some fanfictions, the moment when Minato sacrifices himself to save the village while Kushina is already dead is extremely emotional. It shows his selflessness and also the love he has for the village and his family. Also, the flashbacks in some stories about their early days together, like when they trained together as young ninjas and slowly fell in love, are really sweet and emotional.
It might be due to jealousy. If Minato was getting more attention or praise in the village for his achievements while Kushina felt overlooked, that could create resentment. Say, Minato was constantly being hailed as a hero for his speed and battle tactics, and Kushina, who also had great power, felt like she was in his shadow.
At first, Naruto and Kushina might start to distance themselves from Minato. They could avoid him and not talk to him as much. As time goes on, the hatred might grow deeper. Naruto could start to oppose Minato in public or in important village matters. Kushina might also try to influence others in the village against Minato.
No. In the Naruto series, Minato and Kushina have a loving relationship. A fanfiction depicting abuse goes against the essence of their characters and is inappropriate.
A fanfiction could explore the backstories of these characters more deeply. For instance, how Mikoto came to be so proficient with her sharingan, and how her friendship with Minato and Kushina developed over time. This could add a lot of depth to the existing Naruto lore.
One possible fanfiction could involve Minato, Kushina, and Mikoto working together on a mission. Maybe they have to protect the village from a powerful enemy. Minato's speed, Kushina's chakra chains, and Mikoto's sharingan skills could combine in interesting ways during battles.