On 10 March 1241, she married Landgrave Henry Raspe (born 1204), who was then proclaimed king of Germany by the factions in 1246.

The latter had not been able to sire a child after three years of marriage to his two previous wives, Elisabeth of Brandenburg (1206-1231) and Gertrude of Babenberg.

In November 1247, Béatrice married William II, Count of Flanders, but she was widowed again on 6 June 1251.

Thanks to her the Sisters of Groeninge moved from Marke to a new abbey close to the Leie and the road to Ghent (now Abdijkaai).

Her other mortal remains were given a burial place next to that of William in a lost abbey in Northern France.