Why can’t she sometimes be stupid and mistake the signs that someone could be disloyal, instead of being horribly, horribly betrayed by people she had plenty of reasons to trust?
Or commit stupid blunders that engender disloyalty. This could be a particularly apt force in a society that is built around personal loyalty and honor, like feudalistic societies. If some numbskull repeatedly slights his subordinates without thinking, it's not surprising that some (or all) of them might turn treacherous.
This reminds me of Walder Frey from A Song of Ice and Fire. What he ends up doing is pretty awful and contemptible, but you can see why he ended up doing that - his lord had effectively "betrayed" him according to the rules of their society, and put him in a highly dangerous position.
If she’s got a reputation as someone who goes around recruiting people who are needed to support their families, get the harvest in, or take care of those who can’t take care of themselves, then there’s another source of interesting conflict, and reasons for people to oppose her that aren’t linked to just Being Evil.
Indeed. I don't think we have enough characters with reputations for constantly leading people off on stupid "adventures" and organizing idiotic schemes.