What frenzy dictates, jealousy believes

Nor jealousy Was understood, the injur'd lover's hell.

They play well together because there is no jealousy within the relationship, none whatsoever. The key is that there is no envy with the two of them.

Jealousy is the injured lover's hell

Jealousy is being called up to what you can have, instead of called out for what you don't have.

Lions, wolves, and vultures don't live together in herds, droves or flocks. Of all animals of prey, man is the only sociable one. Every one of us preys upon his neighbor, and yet we herd together.