About the panel where Sovieshu remembered a young Navier eating cookies; it's very significant to the story. That's what the trash Sovieshu will use as reason for his divorce with Navier.
When they were just children and Navier was still a crown princess in training, she had to go through many sacrifices. She had to study a lot and is always on a diet. Sovieshu, out of goodwill, took pity on Navier and stole those cookies from his mother's chambers (the empress before Navier) and gave them to Navier which Navier also shared with him. When Sovieshu's mother discovered that they ate it, she was in a rage because those cookies were special. They had components that would make someone infertile. She was planning on giving those to the emperor's (her husband) concubine. Since then, Navier and Sovieshu were put on a special diet to counter the effects of the cookies and even if Sovieshu's mother knew of the possibility that Navier may no longer be fertile due to this incident, she didn't replace her as crown princess because the empress genuinely liked Navier.
But worry not, as this didn't become a hindrance to Navier and she and Heinley will be able to conceive a child later on. If anything, I think, it was Sovieshu who got affected as the baby Rashta is carrying isn't really his. It was her ex's who is also her first baby (who is under Roteschu's care) baby daddy.