It's been a long time, so the details of the story and character relationships are pretty fuzzy to me, but through my incomplete recollection of the dynamics going on, I feel like that was kind of fucked up of Natsuki to just sit there and watch Asuna go through that. Like, it would be one thing if Asuna was just shy and they were teasing her about it, but Asuna is stuck in the closet specifically at Natsuki's request, and then the two of them forced her into a lose-lose situation there with the perception of real life consequences in the balance all by Natsuki's doing. Just feels needlessly mean, especially for someone who's supposed to be your romantic partner.