Damn, voting but not asking the vote of the sixth member? Don't make me question the initial judgment of your party.
Also, potential new but old comrade in mc territory? I hope so. If they are not going to ask for her vote then they have no right to stops her from doing the same and leaving the hero party.
What I see is,
Hero voted yes because he realized mc reaching his limited, forcefully pushing himself to keep up and as he cares for his well-being but also his own growth that's why he came to this conclusion.
For the glasses waifu(Tiana) she seem to genuinely care for his well being(possibility love) and out of that she doesn't want him to risk his life for the dream she and he know he can't achieve but not leave him saddened/broken also went out of her way to help him as much as she could.
The other two we don't fully know why they said yes, but for what they say it's just the sharp tongue tsun-loli realize mc limited strength and to avoid mc become the cause of her and her party future difficulties said yes(tsun normally have many layers to how they truly feel).
The tall silent dude looks like he just went along with Emma's decision being the right one.