I believe animals can be jealous (usually of someone else getting the attention, and more often if it's a person or other animal they don't get along with)! But they're typically not spiteful or malicious, just worried, mad or scared.

This showed very nicely what a comfort animals can be when you need the world to be less unpredictable and less judgmental. But you also showed what your own constancy has given both of your pets-- and it has transformed both of them! That friendship helps both ways. :)