This is going towards the ending of "Call of the Night", where mc can't reunite with fmc due to author being a dick and making it a bitter sweet ending.
Rea without memories of her traumatizing childhood, but Chihiro being heartbroken.
Well, that's not surprising, it was hinted by Mero interactions with Rea about similarities to her mom, accident their parents and her departure soon after both of them recover afterwards.
Jogoro probably turned Chihiro and Mero mother into a zombie as an experiment, but couldn't preserve her nor stop her from going into Confused State so he frozen their mother in ice.