Librarian and the Bear by Rebel Carter

Your mate isn’t supposed to reject you, right? Well, Birdie’s did. JFC. Now what?

When Birdie Salazar found her mate, she thought it would be a cause for celebration, that her world would finally be complete. Except that when the long awaited day arrives he rejects Birdie before she can even tell him her name.
But it’s okay, or at least it will be.
So what if she can’t stop thinking about him and the pain she feels when she sees him with another woman nearly brings her to her knees. She’ll get through this.
She will.
Just because fate decided to give her an ungrateful Fae mate doesn’t mean she has to live with a broken bond that feels like a knife in her chest. Their world is one of magic and that means the solution to fixing the wound of her broken mate bond is just one Fae witch away. Birdie’s mate will find out that he’s not the only one that can reject their bond, and if he realizes what he lost, well that’s just too damn bad.