What, the fair Ophelia!
Queen:Hamlet Act 5, scene 1, 242–246
[Scattering flowers] Sweets to the sweet, farewell!
I hop'd thou shouldst have been my Hamlet's wife:
I thought thy bride-bed to have deck'd, sweet maid,
And not have strew'd thy grave.
When Hamlet's mother, the queen, delivers "Sweets to the sweet," she's not bearing a hostess gift or offering candy to her date. The queen's "sweets" are funeral bouquets scattered in the grave of Ophelia, Hamlet's former flame.
The prince, who has just finished addressing the skull of Yorick [see ALAS, POOR YORICK], stumbles upon the funeral, ignorant that Ophelia has likely committed suicide. The murder of her father had driven Ophelia mad; Hamlet was the murderer, and the queen a witness. This is all bad enough. But the queen's elegiac nostalgia for her son's courtship of this deceased "sweet" is all the more disturbing in light of Hamlet's somewhat over-arduous attachment to his mother.
It's therefore ironic that "sweets to the sweet" has become a corny quotation for those special romantic moments. How effective the line proves depends on how vividly one's "sweet" is likely to recall the graveyard scene in Hamlet. You might, however, find these bons mots most winning when offered with a willow branch and a whiff of charm to a soon-to-be-insignificant other.