idk man, I work and in my off time, I don't find myself just hanging out and having fun with my kids all the time. There's shit to be done. Sure, once or twice a week we do something like that, but not every day. And when my wife was staying home, it was the same.
That's not to say that life is especially hard for stay at home moms, it's not. It's just a different set of issues and some people deal with them well, some don't. The main issue I've seen people complain about is feeling isolated from other adults. My wife dealt with that when we were in a similar situation to lurkingdirk. Strangely enough, pointing out that it was her own fault for not engaging more with local groups/meetup opportunities did not go over well.