Prey by Michael Crichton, Day 1 10:04am

I never intended to become a househusband. Stay-at-home husband. Full-time dad, whatever you call it - there's no good term for it. [p7]

And her kicking foot made me notice she was wearing sling-back high heels. What she used to call f*ck-me shoes. [p18]

And then I realized everything about her was different - her manner, her appearance, her mood, everything - and in a flash of insight I knew why: my wife was having an affair. [p18]

I had read somewhere that this was a syndrome. The husband's out of work, his masculine appeal declines, his wife no longer respects him, and she wanders. [p18]

"There is no lens."
"How can you have a camera with no lens?"
"I'll explain that as we go," she said.
Watching, I said, "It must be a camera obscura."
"Right," she said, nodding. [p24 - I forgot about obscuras :) ]