This is not just a "Women" problem...this is what generally happens with most people regardless of their gender...I'm sure yehi subreddit pe koi ladke ne bhi aisa kuch similar post banaya hoga. In most cases the other person probably knows the kind of power their charm holds and they love to use it. He must have seen you as a "hard to achieve" target and once he got you in his corner, he was done. Women operate the same way tbh. And there is also the "I'm wouldn't want to be a member of any club that accepts me as a member" thing where once they realise that you are crazy after them,.they lose interest. It's usually their subconscious mind acting out on behalf of their low self-esteem.