George Eliot is, of course, chronicling a variety of marriages, but in particular she seems to be examining male weakness versus female strength. And here's the problem with the marriages that go bad: in all cases, the husband enters the partnership convinced that he is stronger than his wife. Lydgate and Rosamund, Mr. and Mrs. Bulstrode, Dorothea and Mr. Casaubon. Unhappiness ensues. But in the good marriages, the man enters the partnership with full cognizance of his own weakness: Fred Vincy and Mary Garth, Will Ladislaw and Dorothea, Mr. and Mrs. Garth, Celia and Sir James. Thus, both sides are attuned to failure, and modesty, and need. They know how to adjust for one another.
The women, on the other hand, are always aware that they are both powerful and weak. Sometimes they use that awareness poisonously: Rosamund, for instance. Sometimes they are deluded about what exactly constitutes their strengths: Dorothea, for all her glory, is an idiot. But all know they are composites of power and submission and that their lives will require them to ride that riff.
Anyway, if you have your own thoughts on this matter, let me know. For now I'm off to bake bread, which for the record is an incredibly stupid thing to have to do when it's 90 degrees on the 45th parallel (which runs through my living room, by the way). But sandwiches require bread, and men who spend all day fixing other people's houses require sandwiches, and there's a power and submission riff playing itself out in my own home, just as there should be, and maybe we will just have to eat chicken salad and fresh bread in the basement tonight.