I think the reason why Sheieh's placing more blame on Lois is because she "loves Clark", while Clark doesn't.

First of all, I would disagree. Clark admits that he loves her as a friend. Therefore, he should care about her happiness as well.
And the fact that he keeps asking her if she is okay and what is wrong is certainly evidence of that.

Second of all, I would also agree with Ann that Lois has shown some signs of "unselfish love."
When she asked HIM if he was happy in one of the earlier posts. And the fact that she's willing to accept he will leave her is a big one. Certainly part of that is because she's trying to gaurd/prepare herself because she knows it happening. But I think part of it is because she believes Clark will be happier with Lana. So she's willing to let him go, even though it will rip her heart apart.

These chapters are very hard on Lois, I'm not denying that.

But personally, I'm glad that Clark is still wondering about Lana, and seems to what to care for Lois mostly for the baby's sake.

Why?

Because, as I've said before, if he acted otherwise, it would assume sex solves everything. And that's not a fic I would want to read.

Also, I really think if Clark said he WAS in love with Lois, I would believe he was forcing himself to do so because it was the "right thing to do", rather than because he REALLY was in love with her.

And as hard as this is for Lois, I honsetly believe that would be a lot worse. Clark would act like he loved Lois for a while. Then he would run into Lana and all his old feelings would come back. Or something like that. And Lois would be three times as hurt because she believed Clark DID love her, only to have that ripped out from under her.

You need to be honest with your feelings. And right now, Clark is being honest that he cares for Lois like a friend, but is not in love with her.
And this is where the "double-edged guilt" comes in, which I am definitely seeing right now. (read the 89/90 thread, I believe, for more details on what that means.)
EDIT - I just checked, and I guess it's the 90/91 feedback thread.