I think HM has a very good point. Eve is the parent, the older and more experienced one. She has attempted to dissuade Paige from seeing JJ from Day 1, wayyyy before the sex romp. And Paige knows her mom even went so far as to pretend her father was very ill, and they absolutely HAD to go to CA. She has connived, lied and manipulated, all the while pretending to be the comforting mom.
While it is hard to take that JJ would actually have sex with her mother, the fact remains that Eve actually went through with it. I think Eve has the hots for JJ, and cannot believe it herself, but it would explain why she wanted the second romp. And her constantly calling him, meeting with him with the excuse that "you cannot ever tell Paige".
I don't credit Paige with an ounce of common sense, despite being such a good student, but if she learns the facts, and then just sits by herself, going over all that has gone on....she would see what her mother has done. But again, no one tells each other anything, they all let others jump to conclusions, always the wrong ones. Maybe by July sweeps, Paige will have figured it all out, but....tooooo late.