Gaston rushes down the stairs and takes his coat from his driver, asking him if he looks upset.
His driver says he does.
Gaston throws the coat back on the car and mutters to himself, walking down the street alone.
Walking through Paris he sings "Gaston's Soliloquy," a song mostly comprised at first of how Gigi is such a baby.
The the music changes to a slower pace, and Gaston sits down on a bench in front of a fountain, thinking about how polite she was at Trouville, how much fun it was to spend time with her, how she was never a bore.
"Sticky thumbs are all the fingers she has got," he sings. "Where her figure ought to be, it is not." She's just a child, unappealing and ignorant to the ways of womanhood.
Gaston leans against the pedestal of a grand bronze sculpture. "Of course…" he sings, "I must confess that in that brand new dress, she looked surprisingly mature…" He concedes that she was in fact looking pretty good.
He realizes that he can no longer think of her as a child, that she's blossomed.
A confused Gaston looks out into the middle-distance, registering this new epiphany.
Walking through the park, he begins to sing the title theme "Gigi," about her sudden transformation into womanhood. She's more graceful and more beautiful now, he was mistaken, he was a fool, Gigi's all grown up now, and he may very well be in love with her.
We get Gigi's life passing before his eyes in a montage of her looking adorable.
He walks back through the park in a trance not knowing what to do, exclaiming "Gigi!" again and again. He raises his fist in the air, as if in victory.
Back in the streets, he's running toward the camera happy and breathless, singing with the strength of his newfound love.
As he finishes his song, he finds himself back in the Alvarez courtyard.
Running back up the stairs to the Alvarez apartment once more, he rings the bell and Madame Alvarez answers the door.
Gaston tells her he has an important business matter to discuss with her.