Uuum... Have it ever crossed your mind that "maybe" his other half is you? and because you never met him that he ends up get killed by his power? IF he HAVE a soulmate, don't you think he would found it already and mentioned in the novel instead? It's not like the start of the novel is now when Rachel and Zion is still a child.
So she is so hellbent on the story being the LAW.
She and the brother are dead in the story so more or less to her she is terrified that that’s how she’s destined to go, so she wants to run away as far as possible to make it that she literally can’t die to the heroine and her brother won’t suffer.
Atm she might actually feel that the story is correcting itself due to her every path being cut off to go to the human world she is getting desperate, even if she does like his her outright fear is blocking her from even thinking of humoring the romance
And then there the fact is she is a wolf and he is a dragon sworn enemy.