Ralph absolutely believes women were strictly put on this Earth to serve men, ESPECIALLY him. (Thanks Sandra!) When they do the opposite, it triggers something deep within Ralph.
There is someone we are forgetting: Evan, Ralph spent much of his early life with Evan (yet Ralph has never said one word about him), Sandra may have done her best as a single mom, but Evan would have required most of her time and attention, leaving Ralph as the runt of the litter, legitimately feeling neglected.
Since Evan has Profound Cerebral Palsy (I think, am I wrong?), when he grew big enough for his mother to struggle lifting him, Sandra would be forced with the heart breaking dilemma of getting outside help or finding institutional care for Evan.
When Ralph would be in his early teens, Evan was probably admitted to a care home, Sandra probably visited every day, probably worked too, but for the first time in Ralph's life, he was the apple of Sandra's eye, she must have doted on him, for the misplaced guilt she felt about caring more for Evan over Ralph, she must have killed that piglet with kindness. God Bless the Woman, a single mom looking after two boys, one of them disabled, with a do-nothing lunatic ex-husband who (probably) abused one or both of her sons.
I think Ralph truly hates his step-brother, like how he hates Ronnie. Ronnie probably gave him the gunt by stabbing him (pure speculation but a good one), Evan stole his mommy from him. This may explain Ralph's strange 5 year old's mytho-poetic-Wrestling vision of the world, with Angelic E-Daddies who are never wrong, One designated Antagonist for every actor who must be locked in combat until good (ralph) wins, and women as this Harlot-Madonna figure who must be beaten into a Sandra shape through whining and Ralphy's self abuse until they pity him enough to change.
We don't talk about the Evan angle enough. Think of all the Grifts Ralph could run on behalf of Cerebral Palsy Charities, or livestreaming himself feeding his brother apple sauce?