Now, for a different perspective:
IMHO, and please keep in mind that this is my personal view and doesn't mean I ONLY want this, no, I am quite tolerant but not infinitely.
An Harem, to me, and I believe a LOT of other people (male and female), means that ALL within it are IN a relationship with each other. Whether it is one man, 20 men, 1 woman, 20 women, everyone is IN with everyone else.
That relationship may not be sexual. May even not be physical (no hugs, no kisses). But, they are in a relationship. That also means that no cheating, no sharing, no NTR WITHIN the Harem. Whether it's a full on orgy, or 2somes in a closed room or in full view, they are all IN the Harem, there's simply nothing else to even consider.
We mostly see in this forum (please correct me at will) one man and several women versions of Harem. They are NOT the only versions possible. Every possible mix is alright. All of them mean the same, IN the Harem, everyone is with everyone else. That also means that an Harem with only females is possible, also an Harem of Futas, or whatever else you can imagine. The only parameter that makes it an Harem, is that one... you guessed it... everyone is IN with everyone.
So, unless you specify your particular versions of polyamory, that include an Harem and not the other way around, if you call it an Harem, you set it up with those rules. If you want a different setup, and again there's really no limits except consent (and age of consent), you can't just go and call it an Harem and expect that those that do know what an Harem is, can understand your particulars.
To resume:
- Harem is an all included version of a Polyamory relationship
- Any polyamory relationship can be setup with specific rules of who can fuck with who and when and where and even how.
- Don't call your polyamory relationship an Harem if you place limits, or if you do, expect misunderstandings
Hoping I bring something to the discussion that clarifies the issue.
Peace