Yuna was never ecstatic. Having your father taken away at eight years old after never knowing your mother does that to people sometimes.
Yuna was never depressed. When she became a summoner, the whole village celebrated and congratulated her. And on her pilgrimage, her best friends were there the whole time.
Yuna was never happy. The weight of the world on her shoulders constantly drove her insane. And that boy from Zanarkand, making her feel all confused, that didn't help.
Yuna was never sad. They defeated Yunalesca, the supposed last hope of the world. Now there was no Final Summoning to beat Sin, right? Yay!
Yuna was never frustrated. Long nights contemplating the rights and wrongs of Spira after the whole Bevelle fiasco always just made her day.
Yuna was never in love. Nobody knew about that kiss except her... and Him. But he was gone. Disappeared, back home, with Sir Auron, Sir Jecht, and her father.
But most importantly, Yuna was never crying.
Because she was now High Summoner Yuna, and High Summoners weren't allowed to cry...
No matter how much they deserved to, needed to, or wanted to.