Something to consider about this is how Navier was rumored to be infertile. Which was never really talked about outside of shaming her for it (in the series). Would it be so strange for it to be due to stress? Y'know, something that actually causes such a thing naturally?
I say this because Sovietshu wants a child so badly, yet treats his wife so poorly and forces a bunch of work on her without letting her relax. So he takes on a concubine to bear a child, all while doting on her, and still treats sweet Navier terribly. It's like he wants his Kingdom? Empire? to crumble.