The date and the place of Marina's birth are unknown, but she was born before her father's ascension on the Bulgarian throne in 1292, maybe in his official residence in Kran.

Marina was the elder sister of tsar Ivan II of Bulgaria and Teodora, queen-consort of Serbia.

To meet this threat and the invasion of the Mongol prince Chaka, Smiltsena sought an alliance with Aldimir (Eltimir), the brother of the former ruler George Terter I. Aldimir was accordingly married to Marina and, if this had not happened earlier, was given the title of despotēs and invested with an extensive landholding around Kran.

The regents of Ivan II were unable to strengthen their position, and abandoned Tarnovo to Chaka, who installed himself as emperor in 1299.

Marina may have had a strong influence over the policy of her husband and, after Aldimir's subjugation by the Tsar, she and Ivan Dragushin fled to Constantinople.