Perhaps it is wrong to try to reconcile the opposing tendencies of Middlemarch, not only its passionate airing of the case for extending women's opportunities and its putting them back in their wifely place again, but also its expression of a general belief in progress, "the growing good of the world," simultaneously with its exhibiting of the individual failure of the two main characters to achieve their ideals.(p. xix)
Despite Ashton's abdication of this reconciliation, I think these polarities are (already) reconciled in the text by Eliot's conservative perspective on romantic love. Eliot appears to find romantic love a force that will not be denied; for which sacrifice is either worth it, or for which society encourage people - men and women - to sacrifice (a view that she might complicate, but doesn't condemn).
Will Ladislaw, for example, seems stricken with the most adolescent type of romantic love, a two-dimensional devotedness that probably goes far towards making him among the least-developed of the novel's characters. Notwithstanding his insistence to the contrary, if he couldn't have Dorothea, I'm entirely confident that he'd find someone else in a couple of years time.
Dorothea Brooke, for her part, would no doubt have gotten over Will (whom she doesn't even realize she loves until 786 pages into the book) and realized her St. Theresa-potential if she'd stayed single and been a bit more persistent about finding an Albert Schweitzer (or Mother Theresa) outlet for her money.
Still, Will and Dorothea's love will not be denied (by Eliot, or by Dorothea), and neither Eliot nor Dorothea think it error to give up property for this match, despite its most mediocre results.
Similarly, Mary Garth would have been much better off marrying Camden Farebrother; he's a richer, fuller person than Fred Vincy. With Farebrother, Mary would have had a more interesting life and more possibility for realizing her potential in educational, charitable, humanistic and theological directions. Still, both Mary and Eliot are satisfied that Mary should grow white-haired with the man who "always loved her" since she was a child - even if their marriage entails Fred wasting his education and Mary not bothering to educate their boys.
In the same vein of self-destructiveness, Tertius Lydgate squanders his potential as a medical scientist simply to avoid realizing that he no longer loves Rosamond. ("In marriage, the certainty, 'She will never love me much,' is easier to bear than the fear, 'I shall love her no more.'" p. 652.) He'd rather be without his career ambition than without his romantic love for an undeserving object.
This attitude about romantic love is the narrow conservatism that curbs Eliot's progressivism. She cannot seem to imagine a liberating valence for romantic love, as would be the case if Dorothea married Tertius and the two of them joined forces to reform the health care system in Victorian England - a possibility at which the book hints, but dares not dwell.
Why Eliot couldn't imagine this outcome for her characters is an interesting question. In her own life, her partner and common law husband, G.H. Lewes, was her agent. Plainly, Eliot herself was familiar with partnerships that advanced the professional and economic - as well as sexual and emotional - well-being of both partners. All the same, the men in Middlemarch - Casaubon, Will Ladislaw, Tertius Lydgate, and Fred Vincy - obviate this possibility with their pinched views of ideal womanhood - uncritical devotion, beauty, adoration, goddesses on pedestals.
Perhaps without intending to do so, Eliot has illustrated a dynamic more complicated than her stated belief that society suppresses opportunities for individual realization of potential; in Middlemarch she shows - more powerfully than what she says - that individual's compromises (or refusals to compromise) with their romantic inclinations are as powerful an obstacle as any society has constructed.