When you realise that going to see a solicitor about commencing divorce proceedings might not be such a good idea.
The likely conversation:
"So what is it that has become intolerable about your life together?"
"Well, the absolute last straw was an argument about his insistence, in following a new-fangled recipe, on mixing parmesan cheese into the spaghetti bolognese sauce."
"And this was enough to convince you that after 42 years together it's finally time to call it a day?"
"Yes. It's about control. He wants to mix it in so that none of the people who are going to eat it have any choice or control over the matter. I said it is traditional to allow people to sprinkle if they wish."
Umm, maybe not worth spending £168.00 an hour discussing this.