How did the middle class change the relationship between nobles and peasants?

The middle class created a different class that became the buffer and the melting pot for the nobles and peasants.

Explanation:

In many ways the Middle class of Europe was the middle buffer between he noble oppressors and the relentlessly oppressed peasants in the countries of Europe as serfdom was taking its alt breaths.

It was into the middle class that the peasant would be socially mobile to as the noble ship was rare and almost out of reach.

The noble themselves did not find the middle class that terribly below as they were educated and sophisticated so they mingled with them too.

This created a sort of melting pot for both the parts of the society.