I share your concerns, but there's one thing that gives me hope: Grant Gustin. Grant was the one to go against Barry and Caitlin even dating in the show. He stood firm on this even against the machinations of AJK and DP's attempts to make platonic moments seem romantic.
I don't believe Grant would co-sign a hookup with Caitlin or KF, not even in a drunken, depressed, Iris is gone and I'm in lust, or even a body switch between Cait and Iris situation. Not even Barry's evil time remnant, Savitar, gave Killer Frost a second look when she was trying to flirt with him.
I use to wonder if they'd have Barry and Cait somehow hook up to make a way for a White, non-multiracial, Bart Allen. But I don't believe that would happen because Grant would be against it.
Even though he's not a perfect ally for Candice on all occasions, I do believe that Grant is an ally for WestAllen's pure relationship. Even if Eddie came back in some form, I don't think Candice would co-sign cheating on Barry either. She'd be emotionally drawn to him or sympathetic, but no cheating.
That's what I'm holding on to so I can save my sanity.