Honestly, I don't think that this is the kind of thing I can ignore now that I know about it. I'll try to explain how I came across all of this. I played the game with Shadowheart as the only companion I actively tried romancing. I thought it was great, the slow build up was nice and I thought it felt rewarding. I was randomly scrolling through the feedback threads on Discord and found out that people weren't satisfied with Halsin. Then I found this on Reddit:
Not long after that I found the orgy scene on Youtube. Basically implied that you and the drow twins watched Shadowheart and Halsin go at it. Again, I can't forget that kind of thing. Her romance dialogue points towards her being interested in you and only you and not being okay with an open/poly relationship. The fact she's suddenly turning 180 degrees for Halsin or becomes interested in a foursome is jarring and the fact that this thread exists at all with it probably being at least top 5 in terms of popularity here speaks for itself.
If you can't shake that thought, you can always just get rid of Halsin entirely (thus making it impossible to happen, even "off screen"), and remember that during the orgy, she seems quite displeased with the performances, considering she actively pushes you to join in. Your Tav is apparently better than the 350 year old heavily experienced fuckboy. Might have something to do with all the necrophilia you went through as Dark Urge...
But most importantly, just remember nothing actually happens, because even in these optional moments it's not implied to happen (except the fivesome itself, of course). It's just in your mind because of some inconsistent writing.
