It's not unusual for me to make up some BS answer out of thin air just to get him to quit asking. Sometimes, if the subject really interests him, he'll expand on it to the point where I'd pay real money just to get him to shut up. Often, these sessions are helpful, clarifying those nebulous ideas that I hadn't fully considered.
A typical exchange:
“Have you thought about
“The readers don't need to know that.”
“But it's interesting. You could....”
“Yes, maybe, but why? It's not the least bit important. Why do you do that?”
“Ask about the most unimportant elements?”
“I don't do that. Now, what about...?”
He's gradually learned not to ask what I'm working on because ninety percent of the time it's something I have told him about. I shuffle projects and might work on a dozen different stories in a week. I love the fact that he's interested, but I don't always want to stop what I'm doing and explain what the book is about.
However, in a weak moment, I told him about one of my novels where the psychotic ex-wife of the hero breaks into the heroine's apartment, shaves her cat and duct tapes it to the hood of his car. Yes, it's messed up, but the neighbors find the cat a short time later, call the police and take the cat to the vet. I mention in passing that the cat is at the vet's and he's fine.
Apparently, that information wasn't enough for my husband. “What happened to the cat?” He asked when I got to the end of my explanation.
“What? Which cat?”
“Amanda's cat, Muse. What happened to him?”
“He's at the vet's. I said that. He's fine.”
“But you don't mention him again.”
“So? You don't even like cats. Why are you worried about the cat?”
“I was curious.”
“Forget the cat. He's fine!”
“Whatever you say, baby.” There's a long pause, to the point where I'm busy again and have forgotten about the conversation. “You really need to clear that up.”
“Clear what up?”
“The part about the cat....”
The point I'm making is that little details, things we forget about or think are inconsequential, can bother our readers if left unresolved. My husband, who positively loathes cats, was worried about Muse to the point that it detracted from the climax of the story.
I'm not suggesting that every reader is quite so easily misdirected as my husband, but some are. Those are the people we have to satisfy by tying up the loose ends. Make sure the subplots are resolved. Give enough of an explanation that it sticks with the reader. Keep distractions to a minimum so that the thread of the story isn't lost along the way. A few moments spent on “housekeeping” will prevent the inevitable question: “What happened to the cat?”