Don't beat around the bush, Ann, just tell us how you really feel about Clark.
Sorry, couldn't help it. In many ways I agree with you, but at this point in time (obviously the first season) Lois is dating Superman's mortal enemy, something he knows but she has no clue. If she has no reason to be suspicious of Luthor, why should Clark share his secret identity with her? There's just as high a probability that she'll cooperate with him as there is that she'll use that info to go after that Pulitzer. While Clark isn't an angel for deceiving her, Lois isn't clear either. As yet, she hasn't done enough for Clark to trust her with this secret. Besides, if she somehow let it slip to Luthor, it'd be Katie bar the door 'cause bad stuff's a-coming!
But something has to pop, and soon. This state of affairs can't go on much longer. Is it a clone? Is it red K? Is Clark having a psychotic breakdown? Has he been split into two distinct entities by an evil alien cyborg genius? Or is it something even more devious and evil? Stay tuned!