Why men carry ‘pum pum’ feelings?

He was nice to you until you introduced him to your boyfriend. Instantly his countenance and attitude towards you changed; his smile turned to a smirk and he is dismissive of you and everything you have to say. So what could have caused this? Well, there are several possibilities but the main contender is probably that he is upset that you are the one that got away. This is what is known as ‘pum pum’ feelings.