Walkedthatroad has a good point that no one is covering.
Where exactly can this relationship go? Even if you're able to overcome all the boudary issue with a post therapist/client relationship, if she wants to keep her job, your relationship would have to be in the closet.

That's not a healthy place to grow.

Have you actually discussed the risk to her career? Have you asked her if she's ever crossed that line before with other clients?