It was a silent death that no one ever knew about and Snow promised to take that secret with him to his grave. His brother's wife didn't survive the childbirth and Nivalis was forced to marry another wife to take care of Nova.
Snow didn't see Nova again after that day. He would hear about eh and her exponential growth every now and then, but that was it. He didn't want to be reminded of what he did to his father so he didn't bother coming back to see Nova.
But then one day, all of a sudden, Snow heard the news that Nova was no longer going into dungeons and she was going to become a teacher and Snow couldn't have been more surprised. For a moment, he wondered if Nova learned the truth about their family, but he figured that it was none of his business even if she did. He was living a happy life in the air-based Zephyr family as Lancer's dungeon diving partner and there was no need for him to be bothered by what his family was doing.