My gf is frequently in a bad mood, and we do not have kids, and I regularly clean the whole house while she is at work (we have different work schedules). Also, every woman I've ever dated is in a bad mood way more often than I am regardless of what's going on. While I don't doubt the things you cited in your post are relevant in some cases, in most it seems that women are just in bad moods more often than men, at least when we're talking white, American women. A white, American woman living at the 70th national percentile and 99th worldwide percentile will have 100X the complaints as any the women I've talked to and spent time with in the few third world countries I've visited. It's incredible.