I don't think there would be a lot of fanfiction like that. Hinata has always been loyal to Naruto. In the Naruto universe, their relationship is based on a lot of development and mutual understanding. So it's hard to imagine a scenario where Hinata would cheat on Naruto with Boruto in a legitimate fanfiction.
One idea could be to focus on their anticipation and preparation for the baby. They might discuss names, decorate the nursery, and Hinata could be shown getting advice from her family. Naruto, on the other hand, would be excited but also a bit nervous about becoming a father.
Well, it could be a story centered around a festival in Konoha. Naruto and Hinata are preparing for the festival, and Boruto and Himawari are super excited. But then some strange things start to happen. Mysterious ninjas appear and seem to be up to no good. Boruto and Himawari get caught up in the mystery, and with the help of Naruto and Hinata, they figure out that these ninjas are actually from a far - off land and were just lost. In the process, the family bond gets even stronger.
One interesting plotline could be Naruto and Hinata going on a secret mission together in Boruto's time. They get to show off their teamwork skills that have only gotten better over the years.
One idea could be a story where Boruto and Himawari discover an old diary of Naruto's from his early days as a ninja. Hinata helps them understand the context and the values their father held. They then use those lessons to face a new threat in the village.
The story could also revolve around the relationship between Naruto and Hinata during this time. They grow even closer as they are about to start a new chapter in their lives. Hinata might teach Naruto some things about their family traditions related to pregnancy and childbirth, and Naruto would be eager to learn. This could be a story full of love, family, and the strength to face any obstacles.
Often, they are shown as more mature and experienced. Naruto is still the strong Hokage but also a loving father. Hinata has become more confident in her role as Naruto's wife and as a mother. For example, she might be more assertive in decision - making for the family.
Websites like FanFiction.net and Archive of Our Own (AO3) are great places to start. They have a large collection of fanfics related to Naruto and his family.
There are many fanfics that explore the relationship between Naruto and Hinata further. Some might focus on their daily family life with Boruto and Himawari, like how they deal with Boruto's rebellious phase while still maintaining a loving family environment.
Well, Boruto might be really embarrassed. He could quickly turn around and pretend he saw nothing. After all, walking in on his parents like that would be quite awkward for a kid.