You were Voldemort's granddaughter. You and Theo didn't get along well...but at the Death eaters meeting, your relatives and his parents, announced the marriage between you and him.

Voldemort laid his clammy hands on your shoulders, “There will be a wedding...the families Riddle and Malfoy..will be combined in one. Isn't that great?"

You both knew that opponing wouldn't do anything...so you kept quiet