I am going to attempt a helpful and considerate response for everyone involved in this discussion. If it seems inconsistent with things I have written earlier, well thoughts and perceptions develop over time so there are aspects where my standpoints can shift.
First of all to address the emotional aspect involved which cannot be disregarded. If you develop an emotional attachment to the character Shadowheart in the game, the attachment is going to carry over to your real emotions and you can't help but react to things that you experience. To validate everyone's feelings involved, Jennifer English, the VA of Shadowheart expresses these things on a deep emotional level in an interview here Go to the timestamp for "emotional scene" and a word of caution that this can hit too close to home for some.
Now with validation of feelings and emotions involved, let's also make it clear that feelings are not facts! This doesn't mean that I dismiss your feelings for anything but real, just that they aren't the same as facts.
The fact is that if you are playing a monogamous romantic storyline with Shadowheart, that scene is not intended for you. That is intended for a different audience. The companions are dynamic NPC's, which means that there are different versions of Shadowheart for different audiences. The player has a degree of control over which version of the dynamic NPC they want so that the story can cater to different audiences. In comparison to the Kagha storyline that OP mentions a few times, Kagha is not a dynamic NPC, all audiences get the same Kagha.
Different versions of Shadowheart for different audiences does not necessarily need to be consistent with one another, but of course, if some key parts of her character background is suddenly completely disregarded it becomes jarring and the writing that has been done to adapt the character to the audience isn't very good.
Those who follow a classic romantic storyline between two people involving Tav and Shadowheart get a very consistent experience, with the exception of the banter between Shadowheart and Halsin, which I must honestly believe is a script error that shouldn't be there unless you are pursuing the polyromance arc, it makes no sense otherwise. I know I played that down in my earlier responses based on my personal feelings about the whole thing, but again feelings aren't facts, so how I personally feel doesn't matter. It carries gravity no matter how I feel about it.
For my experience playing through the game with a romance arc that involved only Tav and Shadowheart where Halsin wasn't even around in act 3, the delivery was very consistent and satisfying. And that's my greatest advice for everyone to take away from here, the other versions of Shadowheart that aren't intended for you doesn't matter! It is the audience that want the Shadowheart that indulges in casual sex together with Tav and others that gets the inconsistent experience, but I doubt that audience cares that deeply about consistency because they just wanted to feel some stirring in their pants. The existence of an inconsistent Shadowheart for a different audience should be their problem, don't make it into yours.
Agreed, there's different versions of SH (and probably also of others characters) and you're probably right that is not intended to monogamous audience. But what if you happen to stumble upon that scene as a monogamous player? you would, at the very least, think that it doesn't make sense with her character.
You're basically telling us to turn a blind eye, and I think developers shouldn't allow monogamous player to find that scene. If they intended to do poly/exotic relationships, they should have a least have some kind of code/safeguard that preverts monogamous player to got even the chance to find that scene, and also with the flirting, if certain conditions are met, i.e. monogamous, high approval level, romantic scenes unlocked, characters (not just SH) should stop flirting between themselves.
I think you're seeing her 'heart' and we're seeing her 'shadows'. And she got lots of shadows, try a playthrough and don't recruit right away, you will find her a couple of times through act 1, look the way she treats Tav (specially at the grove). She's written in a way that if you're not feeling sympathetic with her (simping her), she's stray mean/annoying to Tav, and that can be seeing as a way of manipulation.
But that's just my opinion, and might be even wrong...
