I always assumed everyone in the story was a virgin, even the MC, with Nancy being the exception for obvious reasons.
But after the scene with Nova and especially the scene with Alex in the mansion dinner, I have my doubts about these two. Alex was pretty comfortable (or so it seemed) to initiate sex stuff and had no problem jerking MC´s dick and even blowing it. Also, she let´s him cum in her mouth (thank you for giving the choice, Dev) and also seems okay with it. I imagine that someone without experience would have more problems with that. As for Nova, she was a bit reluctant to give the Bj in that scene, but she really went balls deep (pun intended) after a while. My guess is that she must have given a bj at some point, and probably in the Eternum world. Maybe that´s why she was more at ease with it, because it was a videogame still.