If you don't mind sci-fi, you might try
Tymber Dalton's
Deep Space Mission Corps books, of which there are currently four (Ms. Dalton did confirm recently in answer to a Goodreads question that she has plans for up to four more, I believe). I've always found that series to be one of the best in terms of polyamory relationship building. The sex scenes are hot, but they are also organic and seem to flow naturally from the course of events leading up to them. One thing that wasn't clear in your request was if it had to be all focused on the woman or not - this book does have a number of m/m and m/m/m scenes in addition to the ones where the woman is the focal point.
Another really good series that comes to mind is
Maya.Banks'
Colters' Legacy books. The first book is one woman with three brothers, 2nd book is their three sons with one woman, the third is about their daughter and is m/f with BDSM themes, the 4th revisits the group from book 2, and the 5th is the sister of the hero from book 3 and two men. In all multi-partner cases the woman has a true reverse harem. Again, what drew me into this series was the relationship building and how each male's relationship with the woman was different and how they functioned as a group to support her. Maya also has some M/F/M books that focus on the relationship building too -
Stay With Me and
Songbird are two of my favorites by her.
There are other polyamory books out there, of course - most of them published by Siren - but it's been my reading experience that the vast majority of those are thin on plot and thick on sex. A couple other authors who spring to mind for writing decent polyamory are
Bianca D'Arc in her
Resonance Mates series and
Brynn Paulin in her
Daly Way books.
Now if you want some M/F/M or M/M/F recommendations, I could give you quite a few more who write those well.
