My wife is a saint for putting up with my credit card shenanigans. I am constantly rotating the credit cards in her wallet and telling her what to use and where. While she always tried her best, sometimes it was hard for her to remember something that keeps changing.
She does most of the spending so it was crucial for me to get her on board. This was a struggle at first, but now we have a system that makes it simple|
The solution: Label your credit cards
On the back of every card I cut a small piece of paper and tape it. This way, my wife doesn't have to think about it. She gets instant confirmation that she has the right card.
I hope this works for others as well.