I did understand your post, but my point was that some people have felt emotional alienation after experiences during their youth that could conceivably cause them to end up in that imagined scenario. Admittedly, it is far fetched, because emotionally scarring experiences are generally much more traumatic than the causal end of a young love affair (as opposed to it ending from, say, a sexual assault, which certainly has left people emotionally crippled), but I doubt that it is impossible. (As I said before...though he's a fictional character, keep Raymond Shaw in mind here)
The point with Eugene, of course, was to show that this sort of thing happened in the story itself. Eugene did move on from his courtship, but he never really got over it (as he said at the party, Lucy was the only reason why he didn't regret stepping through the bass), and it is pretty obvious that he didn't get over how it ended the second time. With Lucy, I think it might be a bit more complex. After reading the book's text for the street corner scene, I considered that perhaps Lucy felt some responsibility for disrupting her father's happiness (though it isn't explicit in the film, this is in the book:
“I don’t know when I’m coming back. Mother and I are starting to-morrow night for a trip around the world."
At this she did look thoughtful. “Your mother is going with you?”
Which gives it, in my opinion, a completely different tone than the scene in the film). Now, it is one thing to miss your own chances at happiness, but to cause somebody else to lose their chance at it?
Fanny is another interesting case. As somebody who obviously had feelings for Eugene, they went completely unfulfilled, but...instead of getting over it, she let it dominate her life. Considers how she breaks down during the kitchen scene when George and Jack start teasing her: so (please excuse this, ladies) girlish in its sentiments...this is the response of somebody who has lived with her feelings about Eugene for a long time, either through a lack of ability or interest in moving past them.
So, I do agree that it would seem abnormal for Lucy to end up in a similar situation, but I think this film proves that it certainly wasn't uncommon in their midland town.