Gentleman Jole and the Red Queen - Lois McMaster Bujold

One of my favorite all times quotes and my favorite quote of this whole series is: “One corner of his mouth crooked up, then the quirk vanished in a thoughtful pursing of his lips. "He's bisexual, you know." He took a delicate sip of his wine.
"Was bisexual," she corrected absently, looking fondly across the room. "Now he's monogamous."
Vordarian choked, sputtering.”
― Lois McMaster Bujold, Barrayar

So, now I'm very, very [depressed (hide spoiler)]. I am literally [sick to my stomach. Not from the homosexual aspect (which I could care less about) but from the not monogamous aspect. (hide spoiler)]

Why or why would you take one of the best relationships in fiction and change it so irrevocably? The author must have known there would be a backlash especially with the quote above in the beginning of this entire series. The relationship that develops in this book would not have been hurt by redefining this added person differently in my opinion and would have made this a great book in the series because if I could have got beyond this revelation, I would have liked this book a lot more - probably a 5 star. But you can't changed something so fundamental and expect your fans to not be upset, well as least you can't expect this fan to not be upset.