Yes, unfortunately, evil characters will leave if your reputation is 18 or higher. There is a table in the back of the manual where you can see exactly which reactions different party members will have to your reputation.
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Melusine, High Queen of Fluffies, Archbabe of the Order of the Holy Flame and the Laughing Hyenas, &
Official Entertainer Elf of the BG2 Bar
Your voice is ambrosia