Ok, this was weird. And I don't even mean all the stuff with the garbage pile dad. I mean why were there multiple instances of "let alone her virginity" as if that's the most important/pertinent thing about her goddamn sister being missing?
The insinuation here is that she could have been raped in the streets, kidnapped or even fallen into prostitution. Or worse, she could have had a terrible death were she got raped and then killed.
However, what really bothered me in this chapter was how they kept talking all the time about the heroine’s “virginity.” I agree that it may have been an indirect way of saying they were worried that she might have been raped, but I thought this way of addressing it was very poorly done. And to make things worse, in a tense moment of the discussion, why keep showing drawings of the heroine’s sister naked during the conversation? It felt unnecessary to me.
Showing a person naked in that kind of situation is like showing their vulnerable state. Note that she's covering herself up and refusing to look forward with shadows on her eyes in that scene, and her eyes in the background keep shifting right to left as if she's trying to find an escape route. Her father saw right through her, now she's fully exposed, weak and afraid.
It's similar to how magical girl transformations tend to make the girls naked before dressing them up, they're in a vulnerable state before being powered up by putting on the battle dresses. Nudity is used as a metaphor for purity and vulnerability, it's not meant to be sexual.
And yes, the way she mentioned her virginity is awkward here, but I think this is actually well done writing. She's trying to get the sister to realize that horrible things could be happening to her younger sister right now and she came up with two of the worst case scenarios, but she did awkwardly in a single sentence because she also doesn't know how to make the wording better in that situation.