‘Room Service’
Season 5, Episode 15 - Aired March 3, 1998
When Lilith comes to town with news that her husband has left her, Frasier tasks Niles with keeping them from ending up in bed together.
Quote from Frasier
Lilith: Our physical reaction to each other was nothing more than a desperate attempt to reaffirm our own worth.
Frasier: Well, that is very impressive, Dr. Sternin. But I too happen to be a psychiatrist. Let me tell you what actually transpired. This was a passive-aggressive manifestation of your deep resentments towards me. Niles, you were punishing me for my notoriety. [to Lilith] You, for my successful adjustment after our divorce. It is this shared bond that brought the two of you to your palace of sweet revenge.
Lilith: Allow me to rebut. What a crock.
Frasier: It is not!
Lilith: It is so. This is yet another example of your complete self-absorption, which is the reason we could not stay together in the first place.
Frasier: I have a right to... Why am I defending myself?
Niles: If you ask me, you are both off the mark. Last night was about two people, ruled by very powerful superegos, tortured by them, who found a chance, however misguided, to break through and rediscover their ids together. Call me an old softy, but that's how I see it.
Frasier: Okay, then, the three of us have certainly analyzed the crap out of this.