Why did all these women that were raped kept sleeping with the one who took everything awa...

You should read up more. Many women who are raped by people they know or are familiar with, try to rationalize the incident so that they can somehow explain it and get a feeling of normalcy.
It happens very often that at the instant when it happens, the person is so overcome with fear that they freeze and don't fight back, and later, when they think back on it, they wonder whether the fact that they didn't fight back makes it their fault and whether sub-consciously they wanted it to happen.
It's not about being brainless. That's the way many people deal with trauma when they don't get professional help.

You should read my post again. I didn't say anything about them fighting back, I was criticizing the fact that they kept associating with him

That's exactly what I was responding to. Let me reiterate it since you didn't read it properly.
"when they think back on it, they wonder whether the fact that they didn't fight back makes it their fault and whether sub-consciously they wanted it to happen. " and " try to rationalize the incident so that they can somehow explain it and get a feeling of normalcy".

These problems stem from "cognitive dissonance". We have 2 extreme cases here:
Misuzu is driven by fear. She knows that Hayafuji is trash who raped her but in her mind she's torn by a feeling of guilt and shame because she keeps wondering if she somehow invited his attention and caused the rape. This is something a lot of victims go through especially when they are very young (in her case 19 - 20). She doesn't have family or friends she can talk to. From experience, she knows that the only friends she has, Minako, would put the blame squarely on her, because of her experience from when they were in school (Minako blaming her for being overly self-obsessed when she said she was being harassed by boys from another school) and because on Minako's obsession with making her relationship with Hayafuji work no matter what. If the incident becomes public, Misuzu is afraid that she will be left with pain, shame and blame while Hayafuji will be perfectly fine. So, rather than face the situation, she tries to run away. She blocks Hayafuji on her phone but still gives in to his threats when he shows up in front of the school. In Niizuma, she finally finds someone she could talk to and who would love her despite her experiences, and so she is able to finally confront the rapist.

With Reina, it's her need for acceptance. Her first sexual experience is being raped by a man she met on a blind date. She has to somehow make the situation make sense (cognitive dissonance) and so she tells herself that it is the start of her relationship with Hayafuji. She doesn't know what a normal relationship feels like and tries desperately to hold on to the broken one she has now, to legitimize what she went through to get into that relationship. It's a slippery slope where at first it is, "I've already had sex with him, so if I start dating him, then everything will be alright" followed by "I'm already dating him, so as long as I protect this love, it'll be alright" and keeps getting worse. In her case, she had friend she could talk to and who wanted to protect her. But if she acknowledges that Hayafuji is trash who just raped her, then she has to accept that the illusion of love and care she created for herself will all be false.

No body wants to think of themselves as victims of violent assault. People just want to live normal lives and try really hard to protect that normalcy. In the Bill Clinton case a long time ago, there were women who accused him but were criticized for continuing to interact with him after the time when they said the sexual harassment took place. They said the same thing. They did not want to acknowledge they had been harassed and just wanted the pain and shame to go away. So they acted like it didn't happen. If you never experienced anything that made you behave that way, you are lucky and you should be happy about it.