Do you have separate accounts? If she pays for her own meal with her own money, nbd. But I’m guessing since you’re planning a future together you’ll also be commingling your finances at some point (if you haven’t already), and with this in mind I urge you to have regular financial planning and check-in sessions with each other to mitigate frustrations over different spending habits.

I didn’t have parents who were great with money, and I don’t naturally have a great head for numbers, so when I got married I had a lot of learning to do. My husband is the complete opposite and stays on top of things much more than I do, but financial spending, saving, and planning are important to be on the same page about. Personally, if I know we’re saving money for a particular project or trip or something, I make much better choices in the moment.

In your specific situation, my advice would be to agree on an amount you want to spend on the outing beforehand so you’re on the same page. This still gives her the option to modify her order to her tastes, she just has parameters to work within. If she completely disregards that agreement, you can always step it up old school with the money-in-an-envelope method, where you can’t fall back on a debit or credit card if you “accidentally” go over (although if I were in your shoes going this route, I’d stash a card on me for emergencies, but make her sweat just enough she feels the burn of her mistake).