I have to disagree here. It would still be considered assault when there is non-consensual sexual activity. Even if it didn't resulted in harms per se. There is a normal assumption that an assault must have corresponding harms, but that is not always the case. If someone goes for a sensual massage, is lying naked on the table, and the masseur starts touching them in a sensual way, I don't think that would reasonably be considered an assault. However, if someone else comes into the room without the client knowing, and performs a sexual act on them, that could reasonably be considered an assault by an objective bystander, even if the client did not feel harmed by it.