In F. Scott Fitzgerald's novel, The Great Gatsby, I think that Gatsby is both in love with and obsessed with Daisy. Though it has been years since she married, Gatsby still seeks out Daisy's company, and pursues the idea that one day they might be together.
Daisy is unhappy, and Gatsby knows this. He believes that this is enough to make her leave her marriage so that they can be together, as if they have never been separated.
However, Gatsby is living in a world that revolves around Daisy, that he himself has constructed.
Almost five years! There must have been moments even that afternoon when Daisy tumbled short of his dreams—not through her own fault, but because of the colossal vitality of his illusion. It had gone beyond her, beyond everything.
It would seem as though he is chasing a ghost, a dream: a remnant of the past that lives only in the past. And though he seems to sense this, he still cannot let the "idea" of Daisy go. Daisy still cares about Gatsby, perking up at the mention of his name at a dinner party, even admitting that she still loves him, but for her it is not a simple case of leaving one man and picking up with another.
As they finally come face-to-face, he hearts things that surprise him:
“Oh, you want too much!” she cried to Gatsby. “I love you now—isn't that eough? I can't help what's past.” She began to sob helplessly. “I did love him once—but I loved you too.”
Gatsby's eyes opened and closed.
“You loved me too?” he repeated.
For Gatsby, the idea that Daisy loved him also, is a surprise. But there is no indication on her part that she is willing to start where they left off: that what is past is not "now."
Gatsby loves the Daisy of years past, but he is obsessed now with the dream that he has created about that woman of the past, not grounded in reality, and it is impossible, it would seem, for him to reconcile the two.
I have never really thought of Young Goodman Brown as such, but when I think about it, he does share some qualities of the romantic hero (see the first link below).
Brown enters the wilderness to test his faith. The Romantics valued the wilderness and saw it as a place to test themselves (think of Thoreau here) and tap into the power of nature. They rebelled against the order and structure of the cities. Certainly, when Brown leaves Salem, he is leaving the order and structure of the traditional world behind.
The whole black mass could be a dream. As the link states, the Romantic Hero often suffers from hallucinations. Brown's experience in the woods fits that quite well.
Also the Romantic Hero is a man of extremes. Brown, in the beginning of the story, is extremely religious. In typical Puritan fashion, he believes he (and his wife) is destined for heaven. However, as he ventures deeper into the forest, and his faith is in doubt, he certainly becomes obsessed with his rage and goes to the opposite extreme, raging through the wilderness, challenging all things evil to stop him.
Finally, the Romantic Hero is often seems to suffer from melancholy. This fits perfectly with the story's resolution, where Brown ultimately dies a very bitter and sad man.
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