I swear there's something darker to that. Maybe Barb being the disgusting walrus of a woman, with resevoirs of moist sweat trapped in the folds of her crotch like mineral deposits just wasn't cutting it for Bob. Maybe Christian started to look a whole lot sexier by comparison. It might explain why Chris is so casually willing to rape his own son.
"C'mon Chris'chyun. I watched your cartoon, and Sonic Says you can.... win... er... win some pokemon cards if you make daddy happy"
*turns up Scat Singing on the Radio to mask horrified grunting*
Dark shitposting aside, I seriously think the impact that's had on Chris is odd. My only other theory is Chris had penis envy from seeing a dick that wasn't shaped like a 3 inch periscope, or that he wanted to get attention points so tried to copy someone else's traumatic experiences, but diluted it. Barb must have sounded like the Alien Queen's rasping every time she had to roll over to let out a fart, and Chris's night terrors come from seeing your dad naked one time?