Those who love this movie often point to this scene and the lingering close-ups of beautiful actors.
I love this scene for another reason. The film is based on Dreiser's An American Tragedy, and we do indeed get oppressive class structure, a pathetic marriage, a universe where human effort inevitably gets trumped by malevolent circumstance, punctuated by a scene wherein Raymond Burr demonstrates a murder by smashing an oar to bits inside a courtroom.
I love this particular scene for the musical theme, and incidentally for the lovers (Liz and Monty) caught up first in dance and then on the verandah, orchestra still within earshot.
The plans, the passion.
Despite the utter improbability of any social acceptance, they race at doom.
That moment motivates.