He is married to Isobel McDuff.
They got married before 1361.Source 1
unknown-1362
Walter Stewart was born between Ist son John and 3rd son Robert. Probably 1338 due to the DOB of Robert in July 1340.
Robert Albany entered into an indenture with Isobel, Countess of Fife, relict of his elder brother Walter, dated at Perth, 30 March 1371, wherein she acknowledges him to be her lawful heir-apparent, and that, when the Earldom of Fife is recovered and the Countess has got possession of it, she will resign it into the King's hands for infeftment in his favour. In consequence of this he succeeded to that Earldom, and was styled Earl of Fife and Menteith
Robert II King of Scotland
Scottish Monarch. Son of Walter, Steward of Scotland and Marjory Bruce, daughter of Robert the Bruce. He served as Regent for David II twice, while David was in exile in France and again while imprisoned in England. Robert succeeded David in 1371, and was crowned at Scone on March 26. His first marriage to Elizabeth Mure and the 9 children of the union were declared illegitimate, as the couple were too closely related. A Papal dispensation was acquired in 1347, but to many it still wasn't enough. Upon the death of his first wife he married Euphemia Ross, who would become his queen, in 1355. They had four children. The question of the legitimacy of his first marriage would later play a big part in the succession. Robert is thought to have had 21 or more children in total, including at least 8 illegitimate children by various mistresses. It was said about Robert that "A more tender heart no man could have". Most of his 19-year reign was troubled by wars he could play little part in. He allowed his son Robert, Earl of Carrick (later Robert III), to act in his stead most of the time. Old and infirm, he died at Dundonald Castle at the age of 74.