I'm not sure specifically as there could be many different interpretations. It might be about a character named Sakura who is secretly in a deteriorating state, perhaps physically ill or emotionally broken in the context of the fan - made fictional story.
One possibility could be that Naruto has been poisoned by a new and unknown enemy. This poison is slowly eating away at his life force, and he's trying to hide it from his friends and family so as not to worry them. He might be secretly seeking a cure while still fulfilling his duties as Hokage.
It could be a rogue shinobi from Naruto's past who has been biding his time. This shinobi might have developed a new jutsu specifically designed to target Naruto and make him die slowly. He's doing it secretly to cause chaos in the Hidden Leaf when their hero suddenly passes away.
Sakura's friends like Naruto and Sasuke could be main characters. They might be the ones trying to find a way to save her. They could be using their skills and powers to look for a cure or a solution.
Well, it could be about a disease that is slowly taking Sakura's life. Maybe she has some rare illness that the characters in the fanfiction are desperately trying to cure.
One idea could be that the child was the result of a past relationship that Sakura kept hidden due to the dangerous nature of the other person. Maybe the father was a powerful enemy who she had to defeat, and she was afraid of the child being used against her.
A common plot could be Sakura trying to hide her feelings from Naruto while he remains oblivious. This creates a lot of internal conflict for Sakura and comical or tense situations in the story.
Sasuke would also be deeply affected. He might show his concern in a more reserved way compared to Naruto. He could be seen as being more determined to find a solution, using his skills and knowledge to try and save Sakura. He might even feel a sense of guilt if he thinks he could have prevented it in some way.
One possible storyline could be that she sacrifices herself to save her friends in a battle against a powerful enemy. Maybe she uses all her chakra to protect the village from a massive attack and as a result, her life force fades away.