I'm not sure I agree that the female characters need to be "nice." But Larian seems to have tied niceness to approval, and right now the female companions tend to be pretty cold/mean to you if you go around doing heroic things. This is disappointing, because I feel like as a good character I'm locked out of the female romance options (or even just a close friendship) due to not wanting to be an asshole to everyone.
Maybe your good character should stop being such a horndog and forget about boning the evil priestess or the space nazi
