This is a tale responsible for the holiday called Qi Qiao Jie, the native Chinese version of Valentine's Day. Called Tanabata in Japan. Naturally, there are countless versions of this story in Chinese mythology alone. Here is one:

Zhi-Nu was the seventh daughter of the Emperor of Heaven, and she was the celestial weaver of the gods' heavenly robes. One day, while visiting the earth, she met and fell in love with Niu Lang, a cowherd. After their marriage, however, Zhi-Nu's absence was discovered by her mother, the Queen of Heaven. Zhi-Nu was ordered to return to her celestial home, but Niu Lang followed her. The Emperor threw a river between them, but out of pity for (heh) star-crossed lovers, the Goddess of Heaven allowed them to meet once a year. So, on the seventh night of the seven moon, magpies form a bridge for the two to meet. This bridge crosses the Silver River or Milky Way. Niu Lang is the star Lyra or Altair, and Zhi-Nu is the star Aquila or Vega, while the bridge is Cygnus.

Although the holiday has waned in popularity, the story is still well-known. It's referenced in the Faye Wong song, "Falling Star."