My girlfriend is also very sensitive to the effects of cannabis. Whether smoked, vaped, edibles or what-have-you, she reacts poorly if she takes it too far (which sadly, is very easy for her).
In her case, she completely forgets how to talk and coordinate herself, often going into laughing fits, moments of panic, confusion, and demanding cuddles. After a few hours, she's normal and fine, but has really hated these experiences.
The only way she can enjoy cannabis is with something that has a ratio that favors CBD and in a small overall dose (such as a weak edible with food to stretch it out). And sadly for her, on most of these experimental occasions I offered her sativas, which can make some people feel really uneasy and overstimulated.
Best I can figure is that some people are very sensitive to the effects, even to the point where they should consider avoiding cannabis altogether. If they're naturally sensitive and/or have very low tolerance, then their experience will be very strong, even overwhelming. If she's up to try it again, I'd suggest using way less, and spacing out the puffs so she can feel the progression and easily stop when she's most comfortable.