The Lana/Clark romance appeals to me precisely because Lana is Clark's first love. First loves may not be perfect or long lasting, but they are certainly unforgettable and tend to have a strong impact on subsequent relationships. The intensity of Clark's first love is well represented in "Exile", first episode of Season 3, in which Lana tries to bring Clark back to Smallville after he heads to Metropolis under the influence of the red kryptonite ring and is on the verge of becoming a villain.
Clark tries in vain to indulge himself in casual relationships because only Lana is the right girl for him. He is surprised but equally overjoyed when Lana finds him, in contrast to his rude resistance to Chloe, his best friend at the time. Lana also openly and repeatedly expresses her trust and confidence in Clark as the man she loves. Although their romantic relationship comes to a dead end toward the end of Season 3, their love story is no less touching and worthy of discussion.
Smallville Complete Series is a must-have for all Smallville fans!
Disclosure: I have been hired by Warner Bros WBWord division to raise awareness for "Smallville."