Hmm, well I guess Clark should have been better at realizing how worked up Lois was. Still, her attacking him seems a bit extreme. Maybe she figured that he would move to avoid her kneeing him, but since Clark will not actually be injured by being kneed, he did not have enough motivation to protiect himself.
It seems that Lois does know for sure that SM=CK.
If you were going for more in this story, I would guess the next time Lois saw Clark she would yell at him for not having gotten her her engagement ring yet.
