in girlfriend the male lead is a CEO and the female lead is a poor girl who is trying her best and same goes is rich man the male lead is CEO and the female lead is a poor girl who is trying her best.
in rich man the male lead is trying to find his ex girlfriend but he does not remembers her face because he has a disease because of that disease he cannot remember faces but he is trying to find the girl with some kind of name and that girl is the female lead.
and in girlfriend the male lead is trying to find the girl who saved his while he was drowning in water but he does not remember her face but he is trying to find the girl with the birthmark she had on her right shoulder and by kiss. although i have not watched all the episode of girlfriend but i think the girl that male lead is trying to find is the female lead.