The bad news is that in version 2.91 (not in version 2.90), Erevi is now also subject to a decrease of affection, as for the other women.
After the "Perfume" quest, Erevi's affection decreases by 5 each day (after being away for more than 5 consecutive days).
After the "Perfume" quest, Erevi's affection decreases by 5 each day (after being away for more than 5 consecutive days).