Bakasi, please recall this paragraph from chapter 3, when Martha and Lana brought a load of groceries to Janey and Rachel and Martha shared with them about Lois blowing up at Clark.
Rachel silently wondered if the secret Clark had shared was that he was Superman. If that was it, and Lois had blown up over it, the problem was Lois’, not Clark’s. Of course, Rachel didn’t know why Lois might have slapped Clark over that secret, so maybe it was something else.
I was actually a little surprised that no one commented on that paragraph. I thought some FoLCs would read it and say, "Wall, shut mah mouth!" If that happened, no one told me. But it's important to know that Rachel has known for a long time.