I'm guessing this has more to do with the Watchers. Raznith and Tyrae don't seem to particularly care what happens to the MC, as long as they're alive, so the guards are more likely to sexually abuse MC with the two Watchers fully aware that it's happening.
Fennore seems to try to appeal more to the MC emotionally, by gaslighting and treating them like a mother child relationship, so she'd probably stop any sort of attempt at rape, or at least dissuade it just to make it look like she's the only one who cares for MC. So, I'd guess that it's less likely that the guards would sexually abuse MC with Fennore around. At least, that's what I'm seeing based on the three Watcher's personalities. Basically, make it look like she's the only person in your world, and it'd be hard to do that if she just let's the guards rape the MC.