Well, in the end it’s all artistic choice. They’re telling you which can fit your themes. But you could also change that. Look at blue is the warmest color. Blue was love, lust, comfort—it was really just the strength of their relationship. As the blue disappeared from the movie, their bond was breaking apart.
It’s all subjective to the filmmaker. Choose what makes sense for your story and stick to it. Then it could be added to this list.