Phantom

We don't know exactly how Freed died, but we know that the Black Mage was powerful, maybe he managed to sever the bond between Freed and Alfrien, perhaps that was how they were cursed.

Freed being simply human meant that the bond being severed killed him and severely weakened Alfrien.

At least thats the way i see it.

I do believe the Global Maple backstory for Freud supports my theory. In fact, during the First War, the Black Mage tried to recruit the Onyx Dragons, but Afrien flat out refused.