Costanza was a daughter of Manfredi III Chiaramonte, count of Modica and Malta, and a powerful figure in Palermo.
Her marriage to King Ladislaus, took place celebrated in Gaeta in 1389 when she was 12, was calculated to bring her family's financial and military support, and not adversity, to his rule.
The supposed reason for the annulment was either the age of the couple or the accusation that Costanza's mother was living dissolutely in concubinage.
The following year Constance was forced to marry the count of Altavilla, Andrea di Capua, son of Bartolomeo, and protonotary of the kingdom, who was residing in the Palazzo Marigliano, Naples.
At the public wedding ceremony, Costanza was said to have proclaimed to her groom that he should take pride in having the king's wife and queen as his concubine.