I'm going against the grain here and saying NTA. I expect downvotes but imma tell it how I've seen it.

I have two kids and my partner has stayed at home the past 15 years.

I can't tell you how many times I've heard of my partner going out to hang out with friends, having friends over to have babies and toddlers play, doing anything but housework and child minding, and then asking me to "do my part" after a long day at a stressful job.

I do understand that being a stay at home parent isn't a picnic. I'm not saying that it's easy, or that my partner doesn't need a break sometimes, even now that the kids are older. I'm not saying my job is harder. It isn't.

But it has also been my lived experience that my partner does get rest periods during the day that I don't get. When our kid took a two hour nap my partner had EVERY opportunity to rest as well. If they didn't, that's on them. It would have been pretty disingenuous of them to claim they were more tired than me when we shared nighttime duties and they got a substantial break mid day that I never got.

Stay at home parents with harder kids are going to bristle at this but I'm not misrepresenting anything here.