Even if Marya isn't actually dead, her populace and governors have at least all heard that she is. That does TERRIBLE things to stability and prosperity, even in domains with clear lines of succession and a history of unity and identity. In a brand new nation, created by the now-theoretically-deceased regent, and totally reliant on the strength of her rule and personal might for its independence and national identity? I'd have expected worse than that. Typical stability loss for a dead regent and new heir is -3. Count your blessings, man.