Thats exactly what I would do. Show her, don't tell her.
Cut out the affection, don't settle for pecks on the forehead or cheek. If thats the way she's gonna be then so be it, two can play that game. Doesn't mean you act cold, just don't initiate affection or touching, that would be a 180 that may jump start some inkling in her mind that you're not settling for staus quo.
