At first the estates stand opposite the monarch. They can agree with him. But they can also oppose him with hostility.

How does this become a rational relation?

Through mediation. On the monarch’s side, the government mediates. On the side of the estates, there must also be a member that stands in the middle.

An image:

A bridge needs not only two banks. It also needs piers in between. Only the piers carry the load from one side to the other.

Summary: The estates can stand against the monarch with hostility. The relation becomes rational only when a mediating member exists on their side too.