Agnosticism IS the most dishonest position

[R00tKiT]

There are good reasons why we should consider open relationships wrong. You say there are some case where infidelity doesn't violate commitment, I would say this detail is irrelevant, because on average, it does.

Fine...on average.  I certainly wouldn't argue that the usual human compulsions and jealousies don't make an open relationship a long shot for the majority of people - but in stating that this is always wrong, we are stating that it is wrong for those people who can and do engage in just such a relationship without them. 

If you concede that it's mostly wrong, then open relationships being wrong is a safer moral assumption don't you think?

If jealousy is a built-in feature/compulsion then shouldn't we act upon it and not allow infidelity,. Isn't it the most natural, straightforward thing to do?

People engage in all kinds of behavior, it's really not rational to argue infidelity into being moral because a bunch of devious couples were okay with it.

Again.  Why would it be wrong in their relationship?  If two people are in an open relationship, and it is not harming them or anyone else...what...what exactly is wrong about their relationship?

If you insist on squeezing this bad thing about every possibly relationship, I would say you can't possibly know that an open relationship doesn't harm them, it might make the partner feel horribly bad or doubt himself or think about harming this third party.. but there might never be a concrete manifestation of these bad feelings. Again, on average, people act on these feelings and say no to this kind of *relationship*.

And I think this is reasonably sufficient grounds to consider open relationships immoral, or at least... not recommended