Why did they have no reaction on goktug's death?

I've started watching the series, currently in season 3. They just forgot about goktug. Cerkutay spent the most time with goktug. With mongols and being osmans alp. But after goktug's death they're just normal (only boran alp was sad).. Cerkutay named kayi after saltuk. But he just doesn't care about goktug. Nobody even mentioned about him anywhere. Geyhatu killed him and osman let him go.. I just find this series not serious enough day by day.. 😭 Even I'm traumatized after his death..