As for Lana...totally agree, she's scared, and Clark isn't as trustworthy as he seems. Which is why "Promise" is so baffling - why does getting proof that Clark has been lying to her (and telling the truth to Lana's best friend) make Lana want him?

I wonder if it isn't purely practical self-interest: Lex can offer Lana all the protection money can buy, but -- now that she knows Clark has super-powers -- she may have concluded he could protect her more completely than Lex's human security. So she instantly decides to abandon someone she'd claimed to love for what seems to be a better deal. *growls at Lana*