Quote from Niles in The Apparent Trap
Niles: Well, how would you have us behave?
Frasier: Well, why don't you try going back to your former relationship?
Lilith: All we did was insult each other.
Frasier: Yes. You're willing to throw all that away just because of one ill-considered night of passion? It happened. Take from it what you can learn. Move on.
Niles: Well, I learned if you kiss her too fast you get an ice-cream headache.
Lilith: You also learned that I have twice your upper body strength, so shut your pie hole!