I expected Lois to be upset at Clark because now his whole family knows about Navance.
But she obviously isn't. However, HE really believes she blames him. And he doesn't know what to do about it.

That's a lot of the cause of the distance between them.

I suspect some of the rest of the distance is because of what I said in the last FDK thread, though.
Clark kissed Lois because she was there, she was a woman, and he was feeling low.
Of course now he's still feeling low, but it's a different kink of "low." So he's withdrawing from her. And Lois has lost what little security they had in their relationship.