Is it possible she now feels like, "well we only go out like twice a year, this is a special treat, and I want to get exactly what I want!" (Mostly) Joking on that.
My only suggestion (that you didn't ask for) is that if she can't decide between a burger and tenders, maybe you get the burger and agree to split it with her getting the tenders. My husband and I do this (he doesn't love it so we don't do it often) but my sister and I always do it, that way we can get something healthy AND something indulgent