That isn't right. He needs a talking-to, then. I've heard that it can be a common thing for men to just dump all the responsibility of kids on the mom because he works a lot, but being common doesn't make it right.
Back to explanations, it's true that for me, when I'm tired and stressed out, I'll tend to be much less considerate, helpful, polite etc, just because those really do take a lot of energy especially during those times (truly, isn't everyone like that? or at least introverts/thinkers/introverted thinkers? I'm not sure this is an SP thing at all...). BUT it's still not fair for him not to help out when asked, even if he might not notice on his own that you need help right away.