The fact that folks can like a white haired owner of a prostitution racket and a drug dealer but not this cute asian chick, whose only fault was to leave without telling to protect the guy she loved.
We don't know how her father will turn out to be, maybe he is some strong yakuza boss who has connections enough to get rid of MC. If he is powerful enough to locate her back then and tell her to come back, he must be capable enough to tap into her call logs too. She has been scared of her father since she was a child as she has seen him do some dirty work. Maybe she knew MC will try too come with her to meet her father had he knew things back then or they both try to leave for somewhere else and it would only end with him and his loved ones in severe danger so she left without telling anyone anything.