I noticed something in the flashback chapters. And it makes sense in context with other chapters and the title.
Ayako has two personalities. One (I dub the Paragon or first 1/2) that's "mom", and another (I call the Incubus or second 1/2) who is sexually aggressive. Asuka has been routinely assaulted by the Incubus, which explains her sexual confusion, as she has no idea of her mother's condition. There's also asymmetry between the two personalities, as the Paragon is dominant but also unaware of the Incubus, tending to blackout when the Incubus is active. The Incubus is otherwise fully aware of her surroundings when not active, but can only be activated by the Paragon's feelings of sexual arousal or jealousy, or when the Paragon is in deep sleep.
Also the Incubus appears to possess a form of telepathy that she uses to pacify her victims.