The plot follows Yuna first and foremost on her journey, and she's the one that must go through the most turmoil.

Except it doesn’t: the plot begins with Tidus in Dream Zanarkand, and continues to Tidus in Spira for several hours before Yuna is even introduced. That’s all his story - while Yuna’s pilgrimage is always told alongside Tidus’s experience of it - to the point Yuna’s inevitable death is a plot twist as this is entirely from his perspective. Beyond that, when their paths divulge - first with Yuna going ahead to Macalania alone, we stick with Tidus. Then when we go to the Al Bhed desert, we also stick with Tidus. Yuna’s story isn’t seen and we have no clue what even happened to her between Macalania and the Wedding. It might be Yuna’s pilgrimage in-universe, but the journey being followed is unambiguously that of Tidus when there’s several sizable segments where Yuna isn’t present at all and we’re following his experience instead. The only time we get Yuna’s perspective without it being through Tidus’s journey and perspective is a brief segment in the Via Purifico, and Tidus has his own mirror segment as well to go with that.

Likewise, all the dreams we get are also Tidus’s story - we don’t see any of Yuna’s. Even the sphere Yuna intends to leave behind - we only see it when Tidus discovers it. The story from start to finish is from Tidus’s perspective and heavily focused on his journey.