You Should Have LiedBasically, after reuniting at the end of FFX-2, Tidus comes to realize that Yuna has changed too much, and is no longer the girl he fell in love with. He tells her this, and then begins to date Rikku. I guess this is sort of Yuna telling both of them that she would have rather they hid it from her, then telling her to her face or being together in front of her. Or something like that.
Song: You Should Have Lied - Stephanie Mcintosh
Clips: Final Fantasy X, X-2