On a dating site you have access to many people. You do. He does. I wouldn't take it as rejection if he changed his mind. He probably found someone who was a better match than you, or lived closer. That does NOT imply there is anything wrong with you. It implies you were not the one for him. Don't take things so personally and please don't hang all of your hopes on the first guy who responds to your profile. Relax a little bit and be choosy. You will find the right guy in time.