Playing Therapist ?

Best friend has been dealing with a cheating boyfriend for the past 5 months. I have been there for her ever since but is it wrong that I’m starting to get tired of her constant complaints about him? She always complains and bad mouths him but refuses to be with him. He always cheats on her and everytime he does I have to play therapist. I don’t mind but at this point idek what to say because this is a constant thing. And I’m tired of hearing her complain I just want her to be happy. I myself am going through my own stuff and ever since this has started with her man all she talks about is him and all the bad stuff he does to her. What do I do at this point? This is taking a toll on me and I don’t want to be a bad friend.