At some time before 15 February 1248 he married his father's ward Eva de Braose, a daughter and co-heiress of William V de Braose, "Black William", Lord of Abergavenny, by his wife Eva Marshal, daughter and eventual heiress of William Marshall, 1st Earl of Pembroke. Eva's wardship and marriage had been purchased by his father in 1238. Eva is said to be represented by the surviving recumbent female effigy in the Priory Church of St Mary, Abergavenny, most of whose body is covered by a large shield sculpted with the arms of Cantilupe ancient, and holding a heart in her two hands. By Eva he had the following issue:
Sir George de Cantilupe, Lord of Abergavenny, only son and heir, who inherited vast estates aged 3 and died in 1273, aged 22, shortly after having reached his majority and recovered his lands from royal wardship. He married Margaret de Lacy but died childless, leaving his sisters or their issue as his co-heiresses.
Joan de Cantilupe, who married Henry de Hastings of Ashill, Norfolk, whose wardship and marriage her father had purchased from Guy de Lusignan in about 1252. Her moiety of her fraternal inheritance included the vast lands of the Lordship of Abergavenny and Aston Cantlow Castle in Warwickshire, one of her father's principal seats. Joan was buried in the Greyfriars, Coventry, Warwickshire, in the Hastings Chapel, together with her husband Henry de Hastings and her son John de Hastings, 1st Baron Hastings, Lord of Abergavenny, all commemorated by effigies, as related by Dugdale. However Joan de Cantilupe's heart was buried in Abergavenny Priory, and "her effigy there shows her holding a heart in the palm of her hand". The effigy supposedly of Eva de Braose with the Cantilupe shield is also holding a heart, but with both hands. Her sons were:
*John Hastings, 1st Baron Hastings, Lord of Abergavenny, eldest son, who in 1273 inherited a moiety of the lands of his childless uncle Sir George de Cantilupe, including the Lordship of Abergavenny and the Cantilupe seat of Aston Cantlow in Warwickshire. He was summoned to Parliament as Lord Hastings in 1290. His grandson was Lawrence Hastings, 1st Earl of Pembroke, 3rd Baron Hastings.
*Edmund Hastings, 1st Baron Hastings "of Inchmahome", Perthshire, Scotland, summoned to Parliament on 29 December 1299 as "Lord Hastings". He died at the Battle of Bannockburn in 1314, having married but without issue.
Death
Cantilupe died in 1254, at about Michaelmas, 29 September. His death is recorded by his contemporary Matthew Paris in his Historia Anglorum thus:
