For me is difficult to think that the characters are virgins, nowadays people lose their virginity so soon (at least in my country) and thinking about Nami or other character still being a virgin surprise me
, but it makes sense too that some girls continue being virgin, like in the real life, there are people that still being virgin. And if we look at people with depression like the Mc it makes sense.
For me it isn´t a problem if the girls are virgins or not, even i prefer that they aren´t virgins, i usually don´t like the shy girl insecure about having sex because she is a virgin, but i´m good with a character with this personality if is well written.
Nami being virgin makes sense, she is obssesed with the Mc so maybe she is waitting for him to desflower her, other characters like Vic makes sense too, her personality doesn´t fits with the type of girl who fucks around with all the dudes. But there are characters that don´t make any sense to be virgins, like Bella, who is a popular girl and a total bitch, impossible that she hasn´t fucked anyone,just for the pleasure or for lose stress, that type of girl usually fuck because they are angry and want to destress themself
, and of course other characters like Nia who is a naughty girl or Zara, even Amber, they are grown girls.