I'm in love with my friend and she's in a bad relationship

Okay so I have this friend who has been in a relationship for four years now with a man in Florida he's cheated on her twice in two months he made promises to show up and get her 8 times but never shows up and always has an excuse a week ago he was going to dump her for another girl but the other girl rated him out he barely talks to her only just sends faces and one word messages and she know all this and she has the intuition the tell kind of that something is up and I keep telling her he a dirt bag he doesn't really love you someone how loves you wouldn't do that to you and that all he does is takes and tells you what not to and gives you nothing back and we'll I love this girl and I have strong feelings for her and maybe I'm not neutral enough to understand but she just madly in love with him and forgives him left and right and I don't understand why or how and I don't know what to do or say to her anymore cause I really care about her and I'm trying to be here but I'm not sure what to do