@Zephyr247 From what I've gathered from reading several historical Chinese web dramas — so take it all with a grain of salt — men, particularly noble men, weren't supposed to interfere with the back courtyards, aka where all of their women, daughters, etc. lived. They aren't even supposed to be in charge of household finances, they're supposed to be in charge of "outside" things like their careers, businesses, socializing with their peers, etc. His official wife — not a concubine — or the family matriarch (so his mother, or perhaps even his grandmother) is supposed to be in charge of the household, so he can focus on Important Man Business. That's why it's so important to find an intelligent and competent official wife, because she's essential to the day to day workings of your household.
Basically... Because Ol Man's mom dotes on Mingyue (scheming black lotus) so much, the dad isn't aware of half the shit she pulls, or he backs down often because filial duty means that, unless Mingyue REALLY FUCKED UP, what grandma says goes.
Ofc it's also a really melodramatic story and everyone but Su Luxia has a tendency to carry the Idiot Ball. 😂😂😂