In late 1227 or early 1228, Joan gave birth to a daughter, Marie. A few years later, on 27 July 1233[13] Ferrand died in Noyonfrom urinary stones, a disease that he suffered since his capture at Bouvines.[4] His heart was buried in Noyon Cathedral, while his body was interred in the Abbey of Marquette, in Flanders. After the death of her husband, Joan wanted to marry Simon de Montfort, 6th Earl of Leicester, but since he was still loyal to the English crown at this point, this did not sit well with Louis IX, who refused to give his consent. It was during that year of 1233 that Bouchard of Avesnes, jailed since his plot of the false Baldwin was released.[4]
After Ferdinand's death, the couple's daughter and heir presumptive, Marie, was sent to Paris to be educated there, following Louis IX's demands.[14] In June 1235[15]she was betrothed to Robert, Louis IX's brother. She died shortly after, leaving Joan childless.
https://en.wikipedia.org/wiki/Joan,_Countess_of_Flanders