While we generally associate Wilde with witty comedies of manners, this story, despite its dark and ironic ending, is heartfelt and sincere. My view is that Wilde believed in true love and was pained that he could not express what, at the time, were his forbidden desires as a gay man. His love—and also his art, represented by the rose—was trampled by insensitive people. This is not the only Wilde story in which love is the central theme. In The Canterville Ghost, the fervent and sincere intercession of the pure, young Virginia allows the ghost to go in peace to his final rest. 

In this story, on the contrary, the sacrifice of the innocent nightingale, who gives up life itself to produce a beautiful red rose for the student, results in a sad ending. Neither the student, nor the young woman who rejects him, are capable of understanding or appreciating the nightingale's philosophy of life. They are both indifferent toward  the "art" of the magnificent rose produced from the lifeblood of the nightingale. The two young people reject and fling away what is most precious and miss what is most important in life. As the nightingale dies, he articulates a core belief of Wilde's:

All that I ask of you in return is that you will be a true lover, for Love is wiser than Philosophy, though she is wise, and mightier than Power, though he is mighty. 

Thanks for this question- I am a diehard Wildean.

The Nightingale and the Rose is a poignant story about sacrifice, altruism, and selflessness. I, of course felt sympathy towards the Nightingale and disgust and anger towards the student in love, for his carelessless and oversight of the sacrifices of the Nightingale.

What is most important is the imagery of this tale. From the moment the bird decides to sacrifice herself, you can read the most powerful words from Wilde: That precise moment the thorn penetrated the heart, turning the white rose red with the sacrificial blood of the poor Nightingale- to that "one last burst of song" which the moon itself heard all the way to the heavens.

These are just some of the most significant details of this story and just one reason why I think Wilde is the best writer in history.