It's honestly not even that ironic, but actually in character. Sharrans aren't encouraged to have sex for pleasure, that's stated during her entire "romance" path as Dark Justiciar in act 3, and it's why you get none despite her loving you until she finds an elaborate excuse to do so "oops, forgot the feast but have to feast to complete this ritual for Shar, guess you'll have to be my feast". The only time this is stated otherwise is during the Mizora scene, which, being a complete contradiction to an entire story arc, is just false and it's part of why I consider that scene as bad as it is.
