I keep running into an issue where I give a hint to a girl and she still walks out of the exam - is this a bug? Less likely but still possible when encouraging all of the girls
The less comfortable a girl is, the more tolerance she'll lose per action you take (to her or others), the more pressure she's likely to build up. You probably have some rules active that reduce the amount of clothing allowed, ones like "Forced Upperless", and, because she's obeying said rule, without having a high enough naturalism/corruption, she's feeling uncomfortable. Alternately, perhaps you stripped her of some clothing, more than she's comfortable not wearing, and this has the same result of boosting how quickly she loses Tolerance and/or increasing how much pressure she builds up.