In my opinion, the emperor was probably around a lot more than we see since he and Ysis do have a good relationship. Ig the flashbacks make it seem more gloomy and disconcerting since him mother just died and the people around him, who were his mother's allies were more concerned about him being able to maintain his position as the crown prince rather than his emotional well-being, which probably made it hard for him to grieve his mother, along with the fact that she became physically weak after giving birth to him.
As for the emperor getting married soon, I don't actually remember if it's ever been mentioned how long after his first wife's death he remarried. However, the dude was in his prime and probably would've had to get married sooner or later to maintain stability. I think it's hinted further in the manhwa, that the emperor loved the current wife even before, or was at least interested in her but had to get married to the first wife because of political reasons since she was of imperial bloodline, whereas the current empress is from a barony.
Yes and in some chapter it was shown that the current empress was pregnant, and emperor was with her but the crown prince was still coping up his mother death . Emperor didn't even care to think about his child and said he was busy with work but have time to impregnate the current empress. I don't like the emperor at all cuz the only time crown prince was able to meet emperor this entire time when he went to see the new emperor.
I know I am overthinking all this but he was a bad husband and a bad father too..
I am on chapter 35 and it's weird how fl's father aka the emperor bought new wife as soon as the old one died and he wasn't even seen during the funeral and he got new empress pregnant already when his own son was struggling to overcome his mother's death and he wasn't even with his son and when the backstory of fl's brother was shown emperor was never there, I may be overthrowing but things just doesn't add up for me.