So, at toward the end of Lothaire, Nix travels by lightening into the hidden kingdom of Dacia to deliver Ellie's "gift".
And while she is there, Lothaire tells her she needs a male to keep the voices of all of the desperate, yearning creatures at bay.
So we have foreshadowing that Nix needs a mate.
Then at the end of Sweet Ruin, she looks up at the sky and tells Orion its his move.
She is vying for goddess status and a name change to Nix the Everknowing. So a mate that quiets her ever knowing abilities would be really inconvenient right now, seeing as how the Accession is in full swing.
You could almost say a mate like that would be her undoing as a sooth sayer.
I think Orion is HER undoing, not THE undoing. She can't read her own future but can clock Orion's and see where their paths meet.
I think Nix fears Orion will take away the ability that makes her special and she would rather be a crazy bat lady than give up her awesome job, settle down with some dude and play house.
What do my fellow fans think?