TW: Mentions of death and sexual violence.
The FMC's mother sleepwalk every night and always stops at a pond before she goes back to her room, the mc always follows behind her mother and then one day/night her mother drowned.
Then Mc later finds out her mother was r*ped and had her but she never treated her badly because of it. And I think the MC starts sleepwalking too.
Iirc it wasn't a modern era setting