It seems that both partners going to the grocery store is more common than I realized! Honestly, I never would have guessed. In my house, I do the grocery shopping, and I buy food for everyone. That means keeping track of what everyone eats on a regular basis and buying some things that others eat and I do not. I cannot imagine telling my wife I'm not going to buy blueberry yoghurt (or whatever) because she's the only one who eats it, and that she needs to make a separate trip to get it. I'm not criticizing, but it's foreign to me.

I guess a lot depends on one's view of responsibilities. We have household responsibilities, and my wife and I divide them. We end up doing a lot for one another, and there's very little sense of, "I'm not going to do X because only you need that." Having kids makes this a natural dynamic because so much of what we do is actually for them, not for ourselves.