So this boy that I like is dating this one girl. Everybody knows how she goes through boyfriends. She flirts with them while they are dating another girl. They break up with their girl to get with her. Then she breaks up with them. Same thing every time. He thinks that they are going to last forever. He is already so in love with her. He is my friend and I don't want him to hate me for saying this but I don't want him to get hurt. Should I tell him?