Pheobe: I'm sorry. For the last time, why aren't you two together again? ...
Ross: Look, we've been together. Then apart. ... It's just, if we got together again and it didn't work out... I could never do that to Emma.
Pheobe: I know. If you tried to make it more, you might wreck it. Or you might get everything [Rachel & Emma]you've wanted since you were 15.