You can have sex with Vicoria and while you're doing it as long as you still have sanity you can stop at any time(like the stable fuck with Arion), I think the option to fuck her is only available if you're straight or bi and have high endurance.
Thank you! I did that while my character was gay and the game still let me join Arion and Vicoria, so I wrongly assumed that was the only occasion to have non fighting sex with her. Thanks to you I know that there is another WIP game over scene with her.