Carnal Harvest - Robin L. Rotham Western = North Dakota? Well, maybe not but they do a role play that is western themed, so I'll put it in that category.

Hake broke a hip when his ATV flipped and hasn't been able to have satisfying (for him) sex with his wife. When he asks his cousin if it's true that he and his business partner Joe are into 3-ways, he asks if they'll satisfy his wife while he watches. It doesn't turn out exactly like Hake thinks it will, but the results are better than he thought. F/M, M/M and M/M/F/M sex. Whoo! Maybe it was M/F/M/M now that I think about it. Oh, I forgot there was a little M/F/M too. Hot book!