2. He didn’t know how you felt

2.  He didn’t know how you felt

Maybe he didn’t think he had a chance with you, while the other girl’s intentions were obvious. Sometimes you don’t consider the other person as relationship material because you didn’t think there was anything brewing between you to begin with. Nobody likes being rejected, so unless he was dead set on having you no matter what (which clearly wasn’t the case), he’s going to pursue somebody more available.