Impossible to ignore or not, Alyssa genuinely doesn't notice his cock because she's increasingly panicked about how much trouble she's having breathing, trying to tug at her collar and tie with the non-lassoed hand.

When he finally lets her tie go, she gasps for breath, relief and air flooding her body at the same time. It's only then that she feels that hardness poking against her ass, and the truth of what he's doing becomes obvious. "Camden, let me go!" she protests, only to squeak when he wrenches her hands behind her back. "That hurts, you asshole! Fuck you!"

Indeed, the adrenaline that's flooding her body means that she's able to tear one of her hands free before he can finish.