The writers in this series have repeatedly established that Clark is not affected in the same way as other people by "special powers". Time and time again we have seen him be immune to the mind controlling affects of other peoples special abilities (see the episode where he gets his heat vision or the episode where Chloe has the ability to make people tell the truth). Once again we have been betrayed by the writers of Smallville.
What is Clark trying to save Lana from by breaking up with her for good and LYING and saying that he doesn't love her? Shouldn't the great Super-moron be doing just the opposite and telling her the TRUTH so that she can understand what's going on and can be better protected by knowing that Clark can be trusted and has the power to protect her? Why is Clark so obtuse that he can't see that Lana is in danger EVERY episode, whether she knows the truth or not? How can telling her the truth put her in any more mortal danger than what she suffers each episode already?
Since Season 3 Lana has been such a poorly written and misused character. She is justified in hating Clark because he is written as a COMPLETE and utter idiot. He needs to find a backbone and start standing up for what he believes in and what he's willing to fight for. He needs to stop being reactive and become more proactive. He needs to stop making all these spur of the moment, poorly thought out decisions.
Just a completely poor episode all around. Hack-writers couldn't write their way out of a wet paper bag.