The faults in our fandoms

WHAT SHOULD I DO

I feel sick. But like I have a fever sick but my best friends boyfriend is practically cheating on her just because she lives in Florida now. He hugs other girls and calls them babe. She really really loves him. I know if I tell her she wouldn't believe me and we'd loose all the years of our friend ship (before preschool - present). She's like a sister to me and I don't want to lose her but I have no idea what to do.