My husband used to get frustrated when the house was a mess. He didn't seem to understand that being 8 months pregnant with a 2 year old, things just weren't going to get done like before. So we talked about it. He claimed that he wanted to help, but that he didn't even know where to start. He was overwhelmed by how many chores needed to be done (yeah, "welcome to my life," I thought!) So I asked him which chore he likes to do the most, and which he really detests. He said he likes dishes okay, but hates bathrooms. "Perfect," I said! I hate dishes and don't mind bathrooms. So from then on, when he wanted to help out, he knew where to start. And he knew that I wasn't going to ask him to clean the bathroom, which had sort of been a fear of his.
I turned out that my husband wanted to help, but didn't know what to do, and was afraid he'd have to do something he really hated. So instead of doing something, he did nothing, and I thought he was really insensitive and lazy. Talking about it really helped.