I'm wondering if we could potentially compile a list. Most often, this is not portrayed well, either due to writers not understanding it properly or them having bias against it. Well working relationships generally also don't cause a lot of drama, and drama is what raises viewing numbers.

For example there is an episode of House M.D. (S6.E18 Open and Shut) where there's a couple with an open relationship and it looks very functional and on a surface level pretty much almost like my own marriage. Both love each other and the husband goes to support the wife while she's on a sex date with another guy.

However later it turns out that the husband is actually monogamous himself and was lying about some other stuff too, kind of putting everything in a negative light. The whole thing also gets jumbled up by House constantly putting this "extraordinary relationship" in the spotlight and Taub awkwardly proposing an open marriage to his own wife.

Ok, this was 2010 and people had probably a bit more bias against this back then.

There's also a side character in Season 4 of The Good Doctor that is polyamorous, but Claire, one of the main characters, basically tells him "you just want a free ticket to cheating" (paraphrasing).

Anyway, I think a list of good representations could help both people that are already in these relationships understand them better, and give some help to people that are considering this type of relationship a bit better. I'd love everyone's input on this.