Guys please, the discussion reminded me of my son, I don't take it seriously, sorry if it bothers you so much.
I think you're completely ignoring the points people had shown here about the Halsin-SH situation.
If you like Halsin, that's OK. But this is a SH romance post. I wouldn't imagine going to the Halsin post and start defending SH while completely ignoring the points made & the original discussion.
Going back to topic.
I don't think they should change the personalities/preferences of any companion. I do think they should had added foreshadow of it throughout the game. And as I said before, using the approval system in certain interactions would had been a great way to achieve this (IMO).
I think that player should know SH has more sexual experience than it looks like before the cheating/Mizora scene. Heck, maybe even in act 1 she could comment something when you find the orc-ogre scene (just a comment, I'd be too soon in the adventure for such a confection) and later on let player know that, despite her almost childish romance, she got lot of experience.
That way if you ended up in the twins drow scene later on, it would:
1 - Make sense when she says she only wants you for herself your first time together, but is ok with the idea of sharing you.
2 - If you ended up in the fivesome, at least I won't be too shocking.
They don't have to change the whole character, they have to make certain scenarios to make sense.
And of course, they should made something in the flirting system, and when you reject Halsin he should stopped trying to get in the way.