So you have chosen aristocracy. The average inter-aristocracy interval is 417 years +/- 196. See you again in approximately the mid 25th century give or take a few.
Classes are defined by their differing and opposing interests. By definition then, there can be no alignment between them. Capital owners want more labor for less capital, workers want more capital for less labor.
Why? It explains a lot about society and it holds perfectly. That's the definition of a good definition. What's your definition of economic classes?
There is an internal contradiction within our capitalist systems, some people live by selling their labors for wages, and some by leasing their capital for labor (to get more capital). Evidently those two interests are opposed, and ergo leads to issues when one side gains two much power over the other, because the power imbalance is very much not self-correcting.
Classes are used to refer to these groups of opposing intersts. There would be no need for classes if there was no conflict. Things only exist in their opposition to other things.
EDIT: meh. At least aristocracies typically had a connection with the people and tended to not openly attack them or their culture.