I dont get why she doesnt understand , when every one else does .?

okay , here is the story . me and my best best best friend met about 4 years ago . in her high school years she has only dated 3 guys. now she has been and broken up with these guys seperately more than i can count . the guy she is with now stopped calling her for a week and she was planning on breaking up with him but instead he calls and she decides not to go through with breaking up with him . im a girl who is bi so me and her dated twice and broke up twice and she has told me that she likes going out with me better than the others , but the one thing i dont get why she just keeps going back out with a person who hurts her emotionally , ( her friends and family can tell that the guy she is with is a player , but apparently she doesnt ) but my question is why does she keep going out with someone when they hurt her over and over again ?