Nobles, by tradition, avoided the common folk as much as possible. They often sat at a different table from their workers and slaves. To marry a commoner was not only socially unacceptable, but brought shame on the families involved. A noble son or daughter who did this was often disinherited.
Nobles were second only to the king in their respective dominions. Often they had at least one castle with other homes out in the country. They had several knights and other soldiers to protect them. As they were frequently corrupt and greedy, they were often revolted against by their subjects.