It's not the first time. A conservative married woman groans about a back ache. and thinks nothing of saying out loud to me, 'i dont know why. i never had any back problem before marraige. only after marriage it started'. O-ho. I'm thinking - 'Don't tell me you didnt figure out it's the sex.' And no doubt he's putting all his weight on you and asking you to arch your back and shift a bit. And maybe he even does her the favour of slumping at the end of it.