The mosaic of Dionysos and Ariadne.

From the Enc. Britt.: in Greek mythology, daughter of Pasiphae and the Cretan king Minos. She fell in love with the Athenian hero Theseus and, with a thread or glittering jewels, helped him escape the Labyrinth after he slew the Minotaur, a beast half bull and half man that Minos kept in the Labyrinth. Here the legends diverge: she was abandoned by Theseus and hanged herself; Theseus carried her to Naxos and left her there to die or to marry the god Dionysus; or she died in childbirth on Cyprus.

This is the Dionysus variation.