I don't think so personally. I chose to romance Astarion and the first sex scene is a little intense, sure, but it wraps into his storyline well and makes you focus on that more than the "passion" of it all. He himself is of course a flirty person, but only in act 1 if you're romancing him. Outside of that, as time goes on and especially in act 3 he becomes less driven by lust and says it himself. I do not think it is over-sexualized in my opinion, but again I haven't experienced any other romances outside of Astarion and only have played the game once. I understand from the view of marketing it was made to be sexualized in certain ways to draw a demographic in but it really isn't a big part of the game overall.
