Marin married, with the approval of Legionary leader Corneliu Zelea Codreanu, Ana-Maria Ropală in February 1933.

Ropală was the daughter of a Jewish woman who had converted to Christianity and a Romanian army officer.

In December 1936 Marin, along with Ion Moța, participated in leading a small group of Legionnaires into Spain during the Spanish Civil War to present a ceremonial sword to the survivors of the Siege of the Alcázar and announce the alliance of the Iron Guard with Nationalist Spain; they also decided to enlist.

Both Moța and Marin died on January 13, 1937, during the first day of fighting at Majadahonda on the Madrid front.

Their funerals in Bucharest (February 13, 1937) were an immense and widely publicised affair attended by some ministers of Nazi Germany, Fascist Italy, and Francisco Franco's Spain, as well as representatives of Portugal, Japan, and delegates of the Polish Patriotic Youth.