If she doesn't like THE food, why the heck does she need to order the most expensive but "disgusting" dish? Hoping it may turn out? Why not just a salad? Not many people will get a doggie bag full of leftover salad you know.
If there's no interest or appetite in some kind of food, nothing heats up well, at least from my own experience. So better yet, don't order it then throw it away——my own experience as well.
There's no rule for me. Definitely no rule for you or anybody. Everyone can make up their own to follow.