The journey to the Grigolia was long in and of itself, taking many days as they passed through the Altic Ocean between West Genora and Moridia, which covered a large area. Even at a fast pace on water, Rui and Amare still took days to get there, taking a break on whatever patch of land they could find whenever they needed a rest stop.
It reminded them of the days during the Era of Darkness when they traveled the Panama Continent to ensure that the Solution of Harmony was realized, getting to learn more about each other as they slowly fell in love with each other.
The voyage through the true world proved to be a different stage in their story, having already been through a lot with each other.
The physical journey itself was not that difficult.
Rui and Amare could have accelerated it considerably if they went all-out, of course. But Rui didn't want to end up sleeping excessively if he didn't need to, especially together where they were completely vulnerable.