I agree with what DrkRvn said, completely. I think real, long-term polyamorous relationships are probably twice as hard to achieve as real, long-term one-on-one relationships. After all, there's at least one more person added to the mix--but if complications are doubled, well, I'd like to hope joy would be, too! I think that such a relationship (especially if an established couple is planning on expanding) is only possible with trust and honesty.

I like the analogy on the website ID pointed to. Love is not money. It isn't limited in the sense that if you give it to more than one person, you take away from A to give to B. Ask any parent with children. You don't love the first child less when the second is born, right? Your capacity to love expands with the new addition. I suspect true polyamory (not cheating) is like that.

But that's just my 2 cents, feel free to ignore it if you don't agree with it.