Lois & Clark: The New Adventures of Superman - Season 1 Episode 10 Pheromone, My Lovely
Overview: An ex-lover of Lex Luthor spreads a perfume in the Daily Planet and everybody begins to fall in love with each other. Lois falls for Clark, the only one who isn't affected by the perfume and he tries not to take advantage of her. Without the perfume effects, Lex tells Nigel that he is in love with Lois.