No wonder she slapped her. People attack the mom, but she also looks down on her mother for being a mom.
Her mother described part of being a wife-- and mother-- as putting up with infidelity, in addition to implying that mothers give birth to children to take care of them in their old age and to demonstrate their fertility.
On the other hand, Ono already suffered infidelity in her own marriage. She did everything she was supposed to do as a wife, and was never appreciated for it to the point that she was cheated on by a man that appeared to be so earnest when they married. She suffered exactly like her mother, who told her that she should have put up with the infidelity (something she was ready to do, too, if not for her ex-husband's insistence on leaving her).
She doesn't look down on her mother for being a mother. Rather, she's despondent about the prospect of wifehood and motherhood because the most intimate examples she has of it objectively suck, and she's being told that it's
supposed to suck.