S9, E14: It's Valentine's Day and while Clark is out on a date with Lois, he unknowingly becomes infected by gemstone kryptonite, which has magical wish-fulfilling properties. Clark mentions to Lois that he wishes they had a more traditional relationship, so Lois quits the Daily Planet, moves in with Clark and starts planning their wedding. Still unaware of his new power, Clark also casually tells Chloe he wishes she would spend more time watching out for him, so an infected Chloe takes his wish to heart and sets her sights on a new target – Lois.