Both Dany and Cercei showed bisexual leanings by experimenting with lesbian sex. While they both found it tempting, they ultimately found it unfulfilling. I postulate that this is because they were unsatisfied with their roles. Dany enjoyed the experience with Irri, even reaching climax, but was wracked with guilt. Dany naturally fit into the (Dom)inant role, while Irri played the (Sub)missive role. This was too close to reality for Dany, whose anti-slavery crusade was just about to begin