Well! This is some novel! Eliot certainly conveys a brilliant and all-encompassing picture of life in the 19th century. The novel has so much! I'll just mention an area I found interesting--the conflict between one's dreams and visions and the reality of life and one's relationships with human beings. I think the marriages of the various characters emphasize this conflict very powerfully. Dorothea thinks she is attaining her specific vision of life and personal growth when she marries Casaubon. She only gets a dusty spiritless relationship. Lydgate thinks he can incorporate Rosamond into his idealism and love of medicine--he can't--and while she strikes one as almost intolerably annoying and selfish, she was, after all, raised in a certain way{as Bookpossum pointed out previously
}.
There are other significant marriages and I'll touch on a couple. The Garths represent a well-functioning role-centred marriage which nonetheless allows the husband and wife to find happiness and balance without sacrificing their values. Mr and Mrs Bulstrode find a deeper meaning through facing their crisis. Bulstrode learns that a superficial, artificial persona will not protect one from the consequences of one's actions.
What is interesting is that Eliot is doing the exact opposite of the typical romantic novel. She's not interested in the courtship, the methodology of getting her heroine married off (something Jane Austen is sometimes--IMO incorrectly--accused of doing) and then living "happily ever after". She is concerned very much with how people cope with life
after they have made this commitment--how they develop as people. Dorothea and Will must go through considerable self-analysis and emotional growth
before they attain happiness in marriage. So in some ways this is a very unromantic novel--but it is a very realistic one.
There is so much more that one could say about this amazing work!