How did George Eliot use social history as the background of Middlemarch?

Closely linked to society's hierarchy, are ideas about how everyone should act in certain situations. Lydgate proposes to Rosamond because society expects that he should do it. Dorothea is pushed to live with someone else or marry again after she is widowed, because society expects that it is right. People don't necessarily follow these expectations, nor should they; but they do exist, and play a part in people's lives.