I didn’t realize it until just recently, but my first exposure to polyamory was back in the mid-90s. I was reading a duology called Bedlam’s Bard by Mercedes Lackey and Ellen Guon, and (spoilers for a book that’s more than 30 years old) in the second book the three main characters are living together and sleeping together. It’s not explicit by any stretch of the imagination — in fact, I don’t think any sex occurs at all in the second book — but they do share a bed. (A waterbed, which tells you how dated this book is.)
In the mid-90s I didn’t know what polyamory was. The kind of adult stories I was reading online (usually on BBSes) focused more on spanking and sex, and less on relationships. I’m sure there was polyamory in some of them — in fact, now that I think about it, I remember it happening in at least one series — but it wasn’t referred to as such. It was just people in a multi-person relationship. Nowadays, now that polyamory is much better-defined and more people know about it, when I read or write stories where characters have multiple partners it’s made more explicit that it’s a polyamory situation.
Some weeks ago, I bought an e-bundle of every Discworld novel — all 41 of them — from an online reseller. I was in the middle of that when I started reading The Hobbit, and after that I got my hands on the entire eight-book Bedlam’s Bard series — I’d known there were more books but I couldn’t find them online. Then I did. I’m curious to see how the polyamorous relationship between the witch, the elf, and the bard progresses. I’m also curious to see how the books change, because the third book is by Ellen Guon and the fourth and fifth are by Lackey and Rosemary Edghill (who I’ve read in the past, but I don’t remember having an opinion on one way or the other). At the moment I’m almost done with the second Bedlam’s Bard book; after that I think I’m going to go back to Terry Pratchett for a bit — I’m up to Guards! Guards! which is one of my favorites because it involves the Watch. Unfortunately, Eric comes after that and it’s my least-favorite. At least it’s also the shortest Discworld book by far.

Somehow, that cover enticed me to buy the book when I first saw it in the Science Fiction Book Club. The cover really focuses more on the second book than the first; the cover for the version that’s on Amazon is much more evocative of the first book:

The image of Beth (the witch) is definitely more accurate in the Baen cover (the second one), and Kory (the elf) looks far more elf-like and less like a cover model. Also, in the first one it looks like Eric (the bard) is holding some sort of clarinet, when it’s made clear in the story that he plays the flute (as you can see in the Baen cover).
A good cover makes the book. But I guess even a bad cover can catch attention, if you do it right.