If others wants to have as the foundation of their relationships a lie, then that's their call, I guess, but I won't.
A lot of people say that polyamory doesn't have a victim. Cheating does most definitely, whether the victim know it or not. Coming up with bizarre justifications is often very creative, but ultimately it's trying to find a justification for lying to a person with whom you entered a legal agreement, and made promises to.
If someone wants to have a relationship with me, and gives me the story that they aren't happy with their current spouse, then my reaction is "good, in order to have a relationship with me, you are going to need to either tell them about it, and I need to be able to verify that you did, or finish the relationship." I don't want to be caught up in the drama, thanks.
If getting an orgasm is more important to them than acting with integrity towards people who they are supposed to care about, then we have nothing in common.
"Listen, or your tongue will make you deaf." - Native American Proverb