Well, Asuna has set boundaries for herself and is inside those boundaries. In the game, she agrees to virtual sex in any situation, because "it's just a game" and it doesn't matter. For her, the main thing is that Kirito does not find out, because there is no need to put pressure on him. In real life, she does not go beyond voluntary masturbation. Everything else apparently doesn't matter to her. Sending a photo without a face is normal for her. As for her behavior, there is 3 option
1. Asuna and Kirito have been together for so long that they already look more like relatives.
2. Asuna is a hypocritical bitch, and resents Kirito for "cheating in a brothel"
3. Fujino has little idea what a real relationship looks like, and therefore made them so.