411, my husband used to say this about me when we had one small child who did a couple of days at nursery.
I worked like a dog during those hours. I did the housework, organizing, cooking and baking, shopping for food, household and child, all the gardening and outdoor work, DIY, admin, paperwork, filing, dealing with annoying stuff like tax disks, permits, bills, etc, dealing with broken things and tradesmen, etc, etc, etc. The work didn't stop because the child wasn't there for 6 hours.
So I can thoroughly understand what a SAHP does during school hours, gender is not the issue.
Housework and childcare don't stop at the end of business hours, so a couple in which one works in and one works outside the home should indeed share the remainder of the day's tasks when both are home.
The argument re things not being as agreed is moot - no one knows what it's like to have children until they have them, and no one knows how they will change, and everyone has the right to change his or her mind.
There's a lot of emotional and financial abuse happening in middle class marriages where the woman is a SAHM, and it's common for men to use the woman's loss of financial control as an in for various forms of bullying.
Complaining about wife is a very common way for men to try their way into an affair. OW feels flattered, like the 'good' one (according to the professionalized, earning model of female goodness that seems to prevail these days). She too is being controlled by the flattering comparison, etc. Works on her own vanity and competition issues, very clever these men.