I spent the first 32 years of my life without credit.
When it came time to buy a house, I went to a loan officer and asked for advice. He told me to get whatever credit card I could, which was some joke card that costs $50 a year to have and has a $200 limit. I used it, payed it. He also said put X amount in a bank account and don't spend it for 6 months. Just leave it there. Pay off any outstanding debts you may have, like medical bills or in my wife's case some default court thing because her room mates abandoned ship without telling her and she was on a lease.
A year later we bought our house with a conventional loan at 3%.
My point is you don't need credit until you need it. Some cases are more severe, like being stranded when a car breaks down, or buying a car without a co-signer, or just plain being poor and needing to eat. I always got through it without credit until we considered buying a house. Then all it took was a year and a little planning and we were approved for all we needed at a very reasonable interest rate. We're scheduled to pay it off 10 years early even.
So all this hype about building credit, checking your credit score, maintaining some astronomically high rating... it's all BS. It's just to keep you as a consumer doing your part to maintain a healthy economy. I never stress about any of that because I don't care if my day to day credit is in the low 400's. When I need it, I will see it coming, and I will do the same things I did last time.
I wouldn't even invite the stress into your lives. Learn to laugh at what the world claims you "need" and all those impulse buys just disappear into the noise. One day she may need credit to do some standard thing like buy a car on her own, or a house, or whatever. Generally those things are not impulse buys, and if they are you either have bigger problems on your hands, or no problems in life at all. If she does see a purchase like that coming, save up as much as you can in one savings account. Don't touch it. Get a cheap, low balance credit card and play the dumb credit game for a year. Once you get your loan, you can cancel the card.
Live against the grain and spare her from a middle age filled with debt.