Who married Robert III, Count of Flanders?

Robert III (1249 – 17 September 1322), also called Robert of Béthune and nicknamed The Lion of Flanders (De Leeuw van Vlaanderen), was the Count of Nevers from 1273 and Count of Flanders from 1305 until his death.

Yolande II or Yolande of Nevers (French: Yolande de Bourgogne), (December 1247 – 2 June 1280) was ruling Countess of Nevers between 1262 and 1280.