I don't get it

Personally, there should not be any "my money" "your money" in a marriage. Whatever income (single or joint) is made is "our" money. If you have the intellegence to make, and determination to keep a household budget their can and will be "extra" money for things for both of you. Now this becomes more difficult with children obviously. And a budget must be based on a 40 hour week, if you develop a budget based on additional overtime pay or other uncertain sources you are facing a high risk of financial disaster. One of the keys to a sucessful relationship is trust, both parteners should know and understand what it takes $$$$ to operate and manage your home. But that is just my view. I have been married for a total of 45 years, there have been difficut times, but none caused or created over money.