As hard as it is, I wouldn't do anything yet. Stay lovingly detached, let the chips fall where they may.
Who is she and what is she doing when you aren't driving her around and eating up her compliments and charms? Time will reveal this.
Who is to say this isn't just pheromones? Or hormones? (My abusive ex still gave me pants-feelings long after the fact, which really disturbed me. My therapist told me to stick to my guns, and wisely, I did. He's bad news.)
You don't have to make any decisions.