Statistics showed that 33% of players romanced Gale and conclusion was "he is just that attractive!". I think I can challenge that statement. If anything, he is just "that easy", or "easy to please", to get approval rating. Simple politeness will go far with him (and Will, and Shadowheart, even with Lae'sel) and he never objects of accepting a quest.
On the opposite side of the specter is Astarion - the only way to romance him is to be rude, dismissive, and aggressive towards potential quest-givers. Which a) does not make sense (he is a vampire, hiding his nature, who is also well bred and knows how to behave), b) harmful to the play-through, since you simply loose some quests. I can add c) you have to go the evil route, but that can be seeing as a good thing.
May be it is a good thing that one romance you can only get if you are evil (though majority of the players would never see half the cutscene designed by the studio) but system in general ... probably should be looked into. There are no alternative pathways even for the easier romances - you missed a scene because of pressing on with exploring, you are locked out of the further content. Sure, the exact scheme will be figured out eventually, may be even a mod will be created to set the flags right (do hope so), but that locks you on a certain gameplay, and definitely does not feel as "natural way of building up relationships".
May be different weight for different dialogs/actions would help? More emphasis on personal interactions? I am not sure, but right now relationships is anything but natural.
