have you considered that she has no assurances that any promises being made will be upheld?
from her point of view, the dragon gods have only hurt her friends and threatened everything she loves, she has NO reason to trust them!
The dragon gods are acting like her father did, denying her the agency to make her own choices even when she states what she wants loud and clear. The threats to her country are being made BY THESE DRAGON GODS, these threats are not some immutable fact, they have a place of origin, and she refuses to accept ANY of this.
Because she's not the spoiled selfish princess her father sheltered from everything anymore
She's a woman who has seen the world at its best and its worst, and is determined to forge a path ahead with her own hands, with the people she cares about, for the country she cares about
Yona is choosing to have agency, even when gods are trying to strip her of it. Their threats are threats, and she will see this mess they have made and fix it.
The dragon gods are being selfish.
Why do you want Yona to give in to these demands? To bow her head to the ones proclaiming to know what's best for her and her people? Who keep adding threats to what she loves JUST TO MANIPULATE HER INTO DOING WHAT THEY WANT?
The point of Akatsuki no Yona is not that "Soo-Won has always been right to discard all emotion and focus solely on saving the country" OR that "Good emotions are all you need, you must never face any hardship and it will all work out okay"
The point is Yona's journey into finding a 3rd path, a balance.
She can love her father and think he was not fit to be king. She can still care deeply for Soo-Won, and think he makes a better king, and yet be hurt by his actions.
And she can mend all the pain of the past, and stop the cycle of revenge, and stop the cycle of pain and hurt for EVERYONE. Her country, her dragons, her people, her friends.
It's not being selfish to refuse to give in to these demands. It's simply refusing to play by rules others have made which state there are only two paths, when you can see three.