Rodolphus wasn't in a rush to escalate their actions. Not like the night she helped him to his bed when he was drunk. He was more interested in taking his time, in savoring the experience. Once she used to enjoy his touches, used to desire him more than any other wizard, including her own husband. It was impossible for her to not be frightened when they were in such close contact. Being brave didn't mean that one was never afraid. No, being brave meant one did what was necessary even when they were afraid. She would've been a fool not to remember how easily Rodolphus could hurt her if he so desired.