Parting is such sweet sorrow
'Tis almost morning, I would have thee gone—
And yet no farther than a wan-ton's bird,
That lets it hop a little from his hand,
Like a poor prisoner in his twisted gyves,
And with a silken thread plucks it back again,
So loving-jealous of his liberty.
I would I were thy bird.
Juliet:Romeo And Juliet Act 2, scene 2, 176–185
Sweet, so would I,
Yet I should kill thee with much cherishing.
Good night, good night! Parting is such sweet sorrow,
That I shall say good night till it be morrow. [Exit above]
Depending on how gripping you find the first balcony scene in Romeo and Juliet, Juliet's parting may or may not be "such sweet sorrow." In any case, her phrase is an oxymoron, combining contradictory ideas of pleasure and pain. Parting is sorrowful because Juliet would prefer, like a mischievous youth ("wan-ton"), to snare her lover in twisted "gyves" (chains or fetters). Parting is pleasurable, presumably, because doing anything with Romeo is pleasurable. Note the latent sadomasochism of this exchange, and the almost wistful prophecy that Romeo will be killed with too much cherishing.
Juliet's "Good night, good night!" is, incidentally, the thou-sand-and-first and thousand-and-second times she bids Romeo goodnight [see A THOUSAND TIMES GOOD NIGHT].