I cannot help thinking, while finishing up the novel, that The Scarlet Letter is a precursor to Madame Bovary, that Bovary is a version of Letter. Certainly Hawthorne's book was known in France before Flaubert wrote Bovary. Critic Émile Montégut had been writing about Emerson and Hawthorne since 1848, and I believe The Scarlet Letter was being read in France by 1852, when Montégut's essay about Hawthorne's novels was published. Flaubert is supposed to be more of a realist than Hawthorne, but who can deny the network of allegory and symbolism so tightly-woven throughout Bovary, making it almost as thickly unreal as The Scarlet Letter? Flaubert created a surface realism affixed to a metaphorical world; he did not actually create The Realist Novel. I digress, though.
There are differences between the books, of course, but they seem to me quite the same thing in many ways. Both are rather intimate tales of adultery and death by poisoning (real poison in one case, moral poisoning in the other) in somewhat repressive remote locations, with dreams of escape to freedom in the big city. In both novels, the physician husband is seen by the straying wife as the villain of the piece. The two wives are both deeply interested in clothing. The men with whom the wives commit adultery are symbols of a possible new and better life. Did Flaubert read Hawthorne?