 With Clark 's secret no longer an issue , the two begin a real relationship in the season seven episode " Fierce " . Lana becomes obsessed with making Lex pay for all his crimes against humanity , which causes her to develop the Isis Foundation , using $ 10 million she stole from Lex . The Isis Foundation is a counseling center for kryptonite @-@ infected people , but it doubles as a front for Lana 's surveillance on Lex . Her obsessions also begin to affect her relationship with Clark by the episode " Wrath " . Eventually , Lana realizes that , even though she loves him , the only way for Clark to help the world to the best of his ability would be if she left Clark and Smallville for good , which she does in the season seven finale . 
