She has to sacrifice herself AND a friend/guardian of hers to defeat the big baddie of FFX, only to have it come back in another 10 years so some other summoner can do the same damn thing. I don't remember some of the details as I haven't played it in years, and there's some other details that would get really confusing if you don't know the game's world and stuff, but that's the jist of it.
Personally if I had that kind of mission I'd be pretty depressed anyway. :\
