What keeps marin and dory away from nemo?

Marlin and Dory are kept away from Nemo primarily due to the vastness and dangers of the ocean, as well as the challenges posed by various predators and obstacles they encounter along the way. Additionally, Marlin's overprotectiveness and fear of losing Nemo again often lead him to be overly cautious, which hinders their progress. The journey is also filled with misunderstandings and misadventures that complicate their search. Ultimately, it's a combination of external threats and their own emotional struggles that keeps them apart.