“We could have just ordered one dish and split it.”

You are having lunch at a restaurant with your husband. You each ordered one dish, but the dishes were huge and you couldn't finish your food. You say:

We could have just ordered one dish and split it.

(someone) could have (done something)

You say that you "could have" done something when you realize that there was a better day to do something, after you did it. For example, if a good friend is visiting your city and you find out that they got a hotel room, you can say:

You could have stayed with us.

order (food)

You use the word "order" for when you ask for food at a restaurant.

split (something)

To "split" something means to share it equally between people. It's often used in a restaurant setting. Things that people often "split" include:

• split an appetizer (at a restaurant)
• split a dessert
• split the check