X Never Marks the Spot

Yeah, Clark's biggest problem is that he seems to put his lies about himself and what he is in a complete separate category from other kinds of lies. He honestly doesn't seem to realize how much his secret-keeping can hurt people (sometimes literally - he gives Lex concussions to keep him from seeing his rescues! That is not good!) And Jonathan and Martha are a large part responsible for that - though Clark's own friends don't help. Those who do find the secret out (Pete, Chloe, now Lana) always are forgiving, always tell Clark they understand and willingly join in the conspiracy of silence. So it's understandable that Clark simply doesn't realize just how much it hurts people, when he lies to them and they know it.