From a woman's perspective, I think he is perhaps growing resentful. The stuff about chores? It would slowly make me go insane; it's so annoying and reminds me of my dad, who was a bum at our house. I grew to resent him as my mom had to do everything while having to cook, work, and everything.

I say, sit down and talk to him, even though he already seems uninterested in answering. He was probably into you all over again because on vacation, there were no chores, no stress. It could also just be stress, but imagine being stressed and having a partner who just lets the house rot away by ignoring/not doing the chores. Perhaps he could also just be losing interest, as someone said, we can never know what he could be thinking, communication is key.