She really thought you were different.
In the back of her mind, she knew to be careful from previous experiences, but something about you made her leave her guard down. She thought you were the one to change her point of view on guys. She put total trust in you. All those nights talking on the phone, those webcam dates, using thousands of texts to talk to each other for the times a phone call wasn't possible. The conversations exchanged between you two, the things you've told her. How is it possible for you to leave her without a second thought about how she would react? Do you not feel any guilt? Does the fact that her smile disappeared not keep you up at night, making you think about what you've done? Or are you busy talking on the phone with the girl you left her for?