You can try not trying. Say, in a situation in which you'd talk to her secretly hoping for a positive response but not getting it, switch gears and not say anything at all. An awkward pause? Her problem, not yours. Let her figure out how to strike a conversation with you.

In the context of teaching, being able to tolerate an awkward pause is a very valuable skill on the part of an effective teacher. Maybe you can borrow this trick from the teaching profession?