I also worry about the normalisation and coercion for more vulnerable people.
My ex and I were in a LTR which hit a vulnerable patch, I worked away a lot, he was jealous and lonely. He was talked into asking me to open our relationship by a couple in the lifestyle to "make us stronger". He was so utterly convinced it would work, I wasn't sure about it but agreed to try, he could, I didn't want to take other partners to bed, after a lot of discussion.
It was a self serving move by the woman "friend", she wanted ex as a regular partner, that never occured as he didn't fancy her and had quite a lot of choice elsewhere. So a normal couple working through a rocky patch which could have been solved with a better compromise ended up in a terrible situation, neither of us wanted. Whether or not we'd still be together now I don't know but I do know opening our relationship was a shit move we should both own up to. Apparently it's still my fault years on for agreeing to it.
And this is where the show gets it wrong with almost everyone walking away all lovey dovey. Open relationships do not work for everyone nor for every couple, if most of what you show is happy endings more people in vulnerable situations are going to think it's OK if only we let go of our egos and realise your partner going off shagging means they love you more 🙄than if they didn't.
It's completely the wrong message.
As for me I wouldn't put myself through it again, I was young and thought we were able to cope but I was caught out by things that hadn't even occured to me, like his ramped up jealousy about me. It could have been a lot more dangerous too in hindsight.