Personally I don't do any of the "romancing" and think the online sex thing is at best an outlet for the undersexed and moreso bordering on perversion but hey you nameless internet folks gotta' keep being you.
I can't help but think there's going to be an army of Karens at some point beating on Hasbro's door about this at some point.
I'm starting to think that romance in this game is ruining the experience for a lot of peoples (or so it seems).
I can't talk for anyone else so I'll talk for myself; I roleplay this type of games and try to choose the dialogues that are the closest to my beliefs. I've never used the romance options in games that had that option till I played this game (mainly because I thought I would feel weird IRL by doing so) but with this game I said fuck it and when on with the romance.
I was playing Lone Wold (2 party set up) and romancing SH, mainly because she was literally my first joinable character, I wanted Lae'zel (I like to have weird races on my party) but couldn't find her till I had my 2 people team and by that point, was too late for her to join me.
I went through all act one, and we had the kiss scene. I was mid-act 2 (or so I think) but hadn't unlocked her second romance scene yet. Fast-forward to me watching a YT video and discovering that, giving certain circumstances, SH (probably others characters too, I haven't play that long) could start flirting with eachother and there was even an option to a poly/cheating encounter. And I don't know why but I (IRL) got a bit mad, lol. Maybe because by the way the video was made, it made her seems like she used my character the whole game, then I started to find posts about it and got a bit more mad. lol
I still have not seem any explicit scene, I wanted to unlocked it in my game. But to be honest, I don't really cared much about romance in this game anymore. If in future playthroughs I unlocked it good, if not it doesn't matter. If I want to watch explicit content, I know a few different websites for that, not this game... lol
However, maybe what happens is that it does something to our brains and we kinda feel a bit attached to our characters? IDK, all I know is I felt a bit weird when I found my character could get cucked. lol. So now my rule is to romance monogamous character only and when I run out of characters, play the poly ones without romance at all.
PS: much love and respect to people who enjoy romance in videogames, I just think in not one of them.
Edit: By reading OP post again I think I'll also skip Karlach Romance, hopefully the rest of monogamous don't have weird shit on their romance scene. xD