Also holy fuck, you guys are insane. Yes, she used word virgin, but I understood it as her more just following the guys logic, rather than agreeing that only sex with lesbians counts. Remember that it's literally the next scene and it's small text written next to her bubble, so a afterthought.
I think you missed page 26, my guy
Same logic can be applied here, that she is just talking to Black hair using her logic
But even if not, who cares if this manga 'might' define verginity to mean if you still have your wierd membrane, at No point does the MC discount Gay intercourse as being Lesser or not real.
And i say 'might' because it could just as well be simple speech, as to make sure they understand each other.