Usedtobeblonde
I can’t understand how she didn’t know though.
It would seem so obvious to me that my H was spending far beyond our income.
That entirely depends on whether Mr and Mrs Sturgeon had an "our income" or not.
Nowadays, many married couples have his income and her income. They either have a direct debit account into which they each pay half of their joint outgoings for utilities, insurance etc, or divide those bills between them on the principle of "you pay the electicity, I pay the heating and so on"
The husband here may have had an overdraft his wife did not know about, or debts. It is st ill a criminal offence to open letters, including bills and final demands addressed to someone else, nor do married couples necessarily bank with the same firm.
So, yes, it is perfectly possible that a wife might not know, either how much her husband actually earned, or how much he spent. And these days, many husbands probably do not ho w much their wives earn or spend.