The Heart is a Lonely Hunter
Harry is the closest thing we get to a romantic interest in the novel, but labeling him as such might be jumping the gun a bit. He's really more of a companion and a friend to Mick Kelly. He becomes her romantic interest more or less by accident and, after sleeping together, the two abruptly pull back from romance all together. But Mick is definitely drawn to Harry and, if they were both a few years older, Harry could have been a full-fledged, traditional romantic interest.