Why is it such a problem, if a male character ask you for sex? Simply say 'No', problem solved.
It is not the problem. As I wrote in the original post, I found it quite fun that Astarion asked me in my 2nd playthrough (I think).
If was fun, because he just acts like that the whole game, it fits his character.
However being asked by Astarion and Gale and Wyll is my issue.
Sorry, but that really feels forced onto you. And not everyone wants that.
Would be great if you could tell the game what your preference is (with that character), and the game would (largely) respect that.
You can feel free to change your preference during the 2nd play through if you wish, or just stay true to who you are IRL.
But this kind of things should not be forced onto the player that much.