Do you have a girlfriend? If so, what might you have you done to provoke the response from another woman?
Somebody? If that 'somebody' is a friend of yours, I agree with Running away. If not...., well, girlfriends come and go, and, if she wants to be your girlfriend now, well, maybe fate has found its match. But, you probably wouldn't be asking the question if that were so - if you were 'falling' for her at the same time she was falling for you, well, sense and sensibility take a back seat. But, play it very slowly, my friend.
Finally, she might not be falling for you as much as looking for a way out of her relationship. Keep your options open, but, be the perfect gentleman.
ps - take it from me, girls don't fall; they have a plan. "For every fly caught in a web, there was a spider with intentions." (my quote)