Oh, I'm so delighted. It's just the tiniest bit out of character, of course: Yuna really did love Tidus, in the game. But there is such a deep bond between Lulu and Yuna; I've always been moved by the fact that while Wakka was off playing blitzball, Lulu's response when she found out Yuna wanted to become a summoner was to head out on two pilgrimages, even with her lover Chappu waiting for her... or just after he died. But I'm babbling. This is a sweet piece, and given the slight adjustment of having Lulu's feelings just a tiny bit deeper, and Yuna's affections shifted... it works, they sound in character.
Write more please! (And you might check out my "Once a Guardian, Always a Guardian", a less explicit one)