I've got it! It's from Honeymoon in Metropolis!
Lois: Have you ever lived with anyone? I mean, full time. A relationship. With a member of the opposite sex.
Clark: No. Not full time.
Lois: Me neither. Full time. What do you think it's like?
Clark: I guess, scary at first.
Lois: Compromises.
Clark: Forced intimacy.
Lois: Sharing responsibilities.
Clark: Never alone.
Lois: Never alone.
Clark: Nothing like what we're doing now.
Lois: Of course not. This is artificial.
Clark: And temporary.
Lois: A charade.
Clark: An act.
Lois: Pure make believe.
