At first I didn't get the Sarah/Beth reference either, but instead of what others got, I thought it meant that Josef had slept with Beth and Mick was delusional, and that shocked me. But then the last sentence wouldn't have made sense, so I reconsidered and got it.
This is no glitch in your writing, but the power of not spelling everything out and making the reader think. I love it, don't change a word.
Wonderful!
