Multiple times, Janelle has explained (and even Christine has admitted) that her relationship with K was not the same as Christine’s. Christine often said she was jealous of seeing him in “good marriages” (plural, not singular) while hers wasn’t, and she specifically acknowledged that Janelle didn’t have the same issues she did. For instance, Janelle and K were still sexually active with each other until the end.
That's not to say that Janelle didn’t have her own issues with K. She did. That's why she dumped him and rejected his efforts to reconcile. Yet, her actual struggles are referred to as "easy peasy" while her situation is misrepresented in the later part of the book.
Despite that, Christine has repeatedly projected her own struggles onto Janelle in couch interviews and now in her book. For example, she claimed K wasn’t spending nights with Janelle in the RV, even though Janelle herself said he did. She even told Christine directly when she asked her. And by that point Janelle wasn’t even protecting the marriage since she had already told him she wouldn’t reconcile after the Christmas fight.
So what does Christine get out of projecting her struggles onto Janelle when she knows it isn't true? Is it about wanting to universalize her pain? About making K look even worse than he already does through exaggeration? Or maybe about wanting Janelle to share her perspective so she feels less isolated?