Before you guys place all the blame on her, it's important to clear something up. Wakaba has been emotionally stunted, even abused, and that developed into a codependent personality disorder. That makes her prime targets for people like Asakura (sociopaths/narcissists). She still has a bit of decency in her (in the fact that she didn't want to kill him), but she's so dependent on Asakura's "love" that she can't even think of leaving the one person she believes cares about it.
And breaking that cycle feels impossible. So if she doesn't wake the hell up after Asakura shows her true colors, and he leaves her, she's only going to go deeper down the rabbit hole.
This is why more than Asakura (whom, make no mistake, I want to kick in the nuts with a steel-tipped boot), I hate Wakaba's mother even more.