Quote from When Harry Met Sally
HARRY: Would you like to have dinner? … Just friends.
SALLY: I thought you didn’t believe men and women could be friends.
HARRY: When did I say that?
SALLY: On the ride to New York.
HARRY: No, no, no, I never said that.
(pauses and thinks) Yes, that’s right, they can’t be friends. Unless both of them are involved with other people, then they can - this is an amendment to the earlier rule. If the two people are in relationships, the pressure of possible involvement is lifted. (another pause) No, that doesn’t work either, because what happens then is, the person you’re involved with can’t understand why you need to be friends with the person you’re just friends with. Like it means something is missing from the relationship and why do you have to go outside to get it? And when you say “No, no, no it’s not true, nothing is missing from the relationship,” the person you’re involved with then accuses you of being secretly attracted to the person you’re just friends with, which you probably are. I mean, come on, who the hell are we kidding, let’s face it. Which brings us back to the earlier rule before the amendment, which is men and women can’t be friends.