Spoilers for Atlas Shrugged are contained in this post.
Why did Dagny fall for Galt?
(Falling right out of the skies.)
Was her judgment simply at fault
For ditching those two other guys?
She does fall for him, rather than consciously selecting him. She awakes and looks into his eyes and she is already in love. So if her judgment at fault, it's not her conscious judgment, but her subconscious.
It must have been something about his face
That made her heart go tilt -
Eyes that didn't bear a trace
Of pain or fear or guilt.
Branden, in his memoirs, recounts that "Ayn said that she did not intend Galt to be perceived as superior in any important way. He is 'merely more serene within himself...'" [JD p91] Obviously, however, Dagny does experience him as better in some important way for her.
What was it about his identity
That swept her off her feet?
I put the blame on serenity -
That made her feel complete.
As long as we're talking about degrees of serenity, I think Dagny gets a black belt in it herself. She seems to have a more even keel than anyone around her - except Galt himself.
Now, you may think that Galt's unreal,
And I don't wish to argue the question,
But whatever he was, he made Dagny feel
Something approaching obsession.