The nightingale describes the young student as a "true lover", and admires him for :
His hair is dark as the hyacinth-blossom, and his lips are red as the rose of his desire; but passion has made his face like pale ivory, and sorrow has set her seal upon his brow.”
The student characterizes the nightingale's from her singing:
“She has form,” he said to himself, as he walked away through the grove—“that cannot be denied to her; but has she got feeling? I am afraid not. In fact, she is like most artists; she is all style, without any sincerity. She would not sacrifice herself for others. She thinks merely of music, and everybody knows that the arts are selfish. Still, it must be admitted that she has some beautiful notes in her voice. What a pity it is that they do not mean anything, or do any practical good.”
This means that the shallowness of the student is such that he even gave artistic criticism to the altruistically generous singing of the bird.
The female is just as shallow as the student. We do not get a clear characterization of hers except for the fact that the student calls her "Ungrateful" (and dully so), and that she had preferred the jewels and the company of the Lord Chambertain's nephew to the dance, disregarded the rose, and left the student jilted and angry.