The Moon is a Harsh Mistress? The Cat Who Walks Through Walls? A lot of Heinlein's stuff had polyamory at least in the background, it not front and center. Mo

The Moon is a Harsh Mistress? The Cat Who Walks Through Walls? A lot of Heinlein's stuff had polyamory at least in the background, it not front and center. More recently, The Expanse dealt with it. Though, honestly, the other spouses all just felt like 2D cutouts of characters, existing solely to show the "open mindedness" of the main character. I don't think I've ever seen a story that really dealt with polyamory with all the characters having agency. Though, granted, haven't gone out of my way to look for it.