I think there's absolutely nothing wrong with it.
Now before you want to jump on me and start questioning me about my moral values, let me justify why I think it's perfectly acceptable and under what circumstances.
If you don't tell the other lover that you have another partner, then it's cheating. You see, there's a difference between a "polygyny" and "polyamory". A polygyny (many+women) means a man having more than one wife at a time and this only applies to man. Polyamory (many+love) is a romantic relationship involving more than 2 people. And this need not necessary be man whom has 2 lovers because it can be vice versa.
To simply illustrate this, it's like a man having 2 love partners and the 2 partners knew of each others existence and they have given their consent. And then this partner can also be in another relationship with another man whom his partner has also given consent. In this case, even a woman can have two boyfriends at a time provided both the boyfriends have given consent. The magic word here is CONSENT. A polyamorous relationship need not be bisexual or to fulfill one's sexual needs. It's a real relationship involving understanding, commitment and love.
I know having 2 partners or even 3 at a time is nothing new. There are so many men or women out there having multiple dates or spouse but what makes polyamorist better than the polygamist is that they are honest about the relationship. If one hides another partner/relationship, it's called CHEATING! While this is not easy for many of us to digest, they are people whom are involved in such relationships. And they managed to do that because of a strong foundation from the primary relationship before moving on to a secondary relationship.
Poly schmolly, I think it's fun to be a polyamorist. It's not easy. There are rules governing this type of relationships. You can just tell your partner, "I would like shag the other person over there and if you don't like it, you can disappear." It's not like this.
Polyamory isn't free love. All these different flavors of polyamory have their own dynamic, but ultimately, they are all about building relationships, not about sex. The rules of having more than one relationship must be established by the partners and a breach of it would be serious matter - as serious as cheating. Everyone involved in the relationship can not cheat on each other and this is the rule.
I do believe that they are people out there whom are capable of loving more than one person and if they are honest about it, I don't see why this ideology cannot be accepted. While we were taught from young to be loyal to one partner, I cannot help but realise that's the reason why we cheat. If we were taught to be honest and open about the relationship, then wouldn't the relationship be built on trust?
So, before you jump on the bandwagon and declare to your partner that you are practicing polyamory, think of the consequences. Not everyone can accept it. And if your partner can't, that means a no for you too. The foundation of every relationship is trust and honesty
In support of polyamory anyone?