In my own opinion, she has become romantic to prove to you that she is over the relationship she had 3 years ago. She might have felt guilty about the confrontation and you should try to understand that a few months have passed.
That does sound a lot like guilt. When people deny doing something that they obviously did do, they often freak out and try to make the other person look like it was them that did something wrong. I hope she confesses. Good Luck