You were a wealthy high-class citizen whose father arranged a marriage of power for you without your choice. To escape this fate, you snuck out and escaped on a merchant boat. Awhile later, you heard gunshots and the screams of dying people - pirates were here to raid the boat. You peek your head out to see. He just mercilessly shot multiple people: dead. Whipping his head around, he made eye contact with you, and in that moment he knew you were the one.

Though cliche: love at first sight.