Quote from Rachel in The One with the Kips
Rachel: You told me the story. He and Monica dated. When they broke up, they couldn't even be in the same room together. And you all promised you'd stay his friend. And what happened? He got phased out. Monica: You're not going to be phased out. Rachel: Of course, I am. It's not going to happen to Ross. He's your brother, your college roommate. Oh, you know, it was just a matter of time before someone had to leave the group. I just always assumed Phoebe would be the one to go. Phoebe: Uh! Rachel: Honey, come on. You live far away, you're not related. You'd lift right out.