Described as being over-indulged, wilful and wildly extravagant, Isabella – unusually for the times – remained unmarried until the age of 33. She had previously been the subject of various betrothal proposals; however, these had all failed to come to fruition. On 15 November 1351, when she was 19 years old, five ships were instructed to take her to Gascony where she was to marry Bernard d'Albret as had been previously arranged. He was the second eldest son of Bernard Ezi IV, Lord of Albret. At the last moment before departure, however, Isabella changed her mind, and the marriage was called off. Her father does not appear to have been angry at Isabella for her capricious behaviour as he granted her custody of Burtsall Priory in Yorkshire in 1355. He also settled the sum of 1,000 marks "per annum" on her.