Smallville season 7 proved that the reasons Clark (Tom Welling) had for not telling Lana (Kristin Kreuk) his secret were stupid. Despite Lana being Clark’s primary love interest in the Superman prequel series, he didn’t finally tell her the whole truth until the season 6 finale.
The romance between Clark and Lana was the show’s central relationship for several seasons. In the first two seasons, the two had a will-they-won’t-they dynamic that blossomed into a short-lived romantic relationship doomed by Clark’s decision to run off to Metropolis. They remained apart during season 3 and 4, but got back together for most of season 5, until Clark broke it off with her. During all this time, Lana didn’t know about Clark’s Kryptonian heritage, though she was well-aware of the fact that he was hiding something big. Not knowing the truth frustrated Lana for years until she reached a point where she started actively looking for answers on her own.
Easily the biggest obstacle that Clark and Lana’s friendship and romance faced in the first six seasons was Clark’s determination to keep her from knowing the truth about him. However, Smallville season 7 made it clear that Clark’s reasons for hiding this secret never really worked. In the early seasons, Clark feared that other people wouldn’t understand if they knew he was an alien. He had particular concerns about Lana because of her personal history. He was always worried that Lana would hate him if she knew that he was a product of the meteor shower that killed her parents. This was confirmed to be his biggest fear in a season 4 episode.
When they were finally on the same page in season 7, it was revealed that all of Clark’s worries about Lana being upset about his alien nature were unfounded. He acknowledged this in episode 3 when he said, “I don’t know why I ever thought you wouldn’t understand.” Lana also never brought up his connection to her parents’ death, because it never mattered. It would have been irrational and out-of-character for her to blame him for something he couldn’t have controlled.
Lana accepting Clark for who he was came only as a surprise to him and no one else. His parents, Pete (Sam Jones III), and Chloe (Allison Mack) all expressed confidence in Lana being able to understand at one point or another. Lana’s reaction was expected for viewers too, as her devotion to Clark and her character in general had made it apparent early on that her loyalty wouldn’t be tested by the truth. Since honesty was what she wanted most from him, Clark telling her the truth sooner than season 6 likely would have strengthened their bond.
Knowing that Clark was creating unnecessary obstacles between him and Lana is part of what made their dynamic frustrating to watch. This could be why Smallville started adding additional reasons for Clark to keep Lana at arms-length. Though doubting Lana’s ability to understand was the one that he kept coming back to, there were also times when he worried that knowing too much would put her in danger. When Clark finally overcame his fears and told her the truth, she died as a result, prompting Clark to use time travel to undo it. Clark used this reason as justification for a while after, but there were problems with this tactic as well. Even when Lana wasn’t with Clark, she consistently found herself in danger either because of other threats in Smallville or because of her proximity to Lex Luthor.