I think it's fine the way it is. How Ono didn't remember his past cuz he's the reincarnation of Kayo, Chizu is like the reincarnation of Hisa so him not remember his past balances out their relationship.
This actually left me feeling eerie inside. Still, I understand makoto's uncertainty. I would have done the same thing too to my partner. It's completely normal!
This is disturbing and the stories dont make sense... Especially c2. Great smut though