Quote Originally Posted by d£v!l'$ ph0£n!x View Post
i think it reflects how devoted the characters are, sending someone to their death because it's their duty, even though it's killing them to do so
It was Yuna's own decision, and her guardians had no right to interfere.

This is basically how it went on:

Guardians: "You're... ready for this?"
Yuna: "...Mmm..."

Tidus even tried to convince her not to do it, and then she started crying and told him that she had to.