Maybe Videl. She's strong - willed and also into martial arts. They could have met in a different way and their shared interest in fighting could have led to a romantic connection. However, this would change a lot of the existing storylines.
Maybe in this fanfiction, Goku realizes that he and Chi - Chi have very different personalities. Chi - Chi is often more concerned with family and a stable life, while Goku is a free - spirited adventurer. This clash of values could lead him to decide not to marry her. For example, Chi - Chi may want Goku to stay at home and help raise Gohan, but Goku is eager to explore new planets and fight powerful enemies.
In this fanfiction, the story could develop in a way that Goku's decision not to marry Chi - Chi has a ripple effect on the entire Dragon Ball universe. His friends might be shocked and try to persuade him otherwise. But Goku stands his ground. This could lead to new alliances being formed as some characters side with Goku's decision, while others support Chi - Chi. The lack of the Goku - Chi - Chi marriage also means that Gohan's upbringing is different. He may grow up with a stronger sense of independence, seeing his mother as a sole provider, and this could influence his future actions and development as a fighter.
In a fanfiction like this, perhaps Bardock is on a mission in the afterlife and it leads him to cross paths with Goku and Chi - Chi. Bardock could test Chi - Chi's strength and worthiness to be with his son. Chi - Chi would rise to the challenge, showing her determination. Goku would be in the middle, trying to make sure his father respects his wife. And in the end, Bardock could give his blessing to their relationship, seeing how happy they are together and how Chi - Chi has made Goku a better person in many ways.
One reason could be his pursuit of stronger opponents. Goku is always eager to test his strength and find new challenges. In fanfiction, this might lead him to leave Chi - Chi to travel the universe in search of the toughest foes. He might feel that staying at home with his family restricts his growth as a fighter.
Well, it could be really interesting. Maybe Goku would find someone who challenges him in a different way than Chi Chi did. This new love could be a powerful fighter from another planet, and they bond over their shared love for battle and protecting the universe. It would be a big change for Goku, as his relationship with Chi Chi was more about family and domestic life in some ways.
Well, perhaps Chi - Chi meets Goku at a new tournament. Goku is excited to see her, but Chi - Chi is a bit miffed that he didn't tell her he was participating. They then have a heart - to - heart talk about his love for fighting and her desire for a more stable family life. It could be a really emotional encounter with lots of reminiscing about their past and hopes for the future.
Well, their meeting in fanfiction could be really sweet. Maybe Goku finally realizes how much Chi - Chi has been there for him all these years. He might see her in a new light, beyond just being his wife. They could have a deep conversation about their past adventures and how they've grown as individuals.
Some people might create it just for shock value. They know that the original relationship between Goku and Chi - Chi is loving, so by creating something so opposite, they can get a reaction from readers.
In the comics, Shang Chi has been romantically involved with Leiko Wu. Their relationship adds depth to the story and character development.
I'm not sure if there is an actual fanfic with that exact plot. Fanfic topics can vary widely, but this seems like a rather unfaithful and out - of - character concept considering Chi Chi's strong bond with Goku in the original series.