Ideas and Empires

"... and loves are like empires: when the idea they are founded on crumbles, they, too, fade away." -Milan Kundera The Unbearable Lightness of Being

This sentence has been troubling me. If I accept it, it pushes me to a conscious understanding of the ideas my loves are founded upon. Considering the notion of an empire fading away because the idea it was founded on has crumbled, I wonder what the founding idea of my empire has been (and if that idea still exists). In both a love between two people or a society between many it seems as though an understanding of the "idea" has to be shared among the participants. 

I suppose that Kundera's formulation doesn't call for this kind of understanding among all the subjects in the empire. His idea is that when the "idea crumbles" the empire fill follow suit. But how does an idea crumble? Ideas are things that people have, and in a relationship between people it is the shared idea that is the foundation for all else. So it seems as though in an empire like ours (ostensibly a democracy), a great majority of the people are called on to understand the foundational idea or ideas and go forth in the society operating in accordance with the implications of the idea. 

I wonder how many people in the United States share this kind of foundational idea. Or, more importantly, how many people demand this level of clarity and genuine interaction in their lives with immediate others (the ones they love)?