Chazds, I don't know that that's a cut-and-dry rule.
I think that an open relationship has the POTENTIAL to be/do all of what you said, but that doesn't mean that it automatically WILL do/be all of that.
I couldn't make an open relationship work. I'm a bird, as PJ said, and I'm with another bird and we are very happy in our nest. There are some things, sexually, that he's interested in that I'm not, but all in all, monogamy is too important to us to let others climb into our bed just to fulfill those needs.
However, that's just *us.*
If you've got the communication and trust to a point where they're open and honest enough to allow for an open relationship, then you've got a healthier relationship than most folks out there! (there = the vast wide world) My feelings in such a situation would be, "why risk messing it up?" But then again, life is about taking risks. You may try being open and hate it, you may try it and love it, there's a lot of possibilities. I won't pretend to understand the dynamics between two gay men. I'm a straight gal all the way, and therefore never WILL understand, just because I can't. Comes with the ovaries.
Avatar - Isaac, my blue-fronted Amazon parrot. Adopted 9/7/07. Age 30 (my pet is older than me!)