"The Summer Garden" is a short story by Harry Turtledove. It was originally published as "The Summer's Garden" in Fantasy Book, February 1982. It was republished in a form closer to the author's original intent in Kaleidoscope, Del Rey, 1990; and 3xT, Baen, 2004.
The Summer Garden is a fantasy tale, based on a tale from Boccaccio's The Decameron. It is set in the fictional Empire of Kar V'Shem, but makes use of the Medieval notion of courtly love.
A romantic knight, Rand, seeks the hand of Dianora, the wife of a local merchant named Ansovald. Dianora is a kind person who prefers not to cause injury to others. This impulse prevents her from accepting Rand's pleas and hurting her husband. However, she cannot simply dissuade Rand from his pursuit. In desperation, she offers to give herself to Rand if he can produce a garden full of summer fruits and flowers in the dead of winter. Rashly, Rand agrees. He trades his substantial wealth to a mage named Portolis, who, despite warnings against Rand's scheme, provides Rand with the garden.
When she sees the garden, Dionara agrees to go forward, but again asserts she does not love Rand, and that the offer she made was an attempt to convince Rand to end his courting. Rand releases her. Portolis, impressed with Rand's selflessness, returns Rand his gold. Rand lives a life of prosperity.