Dona wants to live happily and become a good person.
But wanting to live happily and become a good person are inherently at odds.
In the end, Dona chooses to live happily. To survive, she must grow strong, strong enough never to be at the mercy of others again.
She must kill every being that would kill her, all so she can live happily.
Even if she has to live all alone.
Besides these things, is there anything else that could make Dona want to stay...?
This is a bleak, chaotic story, but it is by no means a story of death and finality.