It isn't the structure of a relationship that leads to dishonesty. It is the people involved and how ethical they are willing to be. I think that focusing on whether or not the relationship is open or poly is not the place to zero in on.
The point of focus should be on: 1.) the communication between you two, and 2.) following through on the commitments you make. Acting with honesty and integrity, basically. Whether those commitments are to exclusivity or non-exclusivity makes no difference.
Each of you must figure out what you truly want and where your own personal boundaries are, ask for what you need, deliver consequences when boundaries are crossed, live up to your commitments, learn how to forgive and yet use "tough love" at the same time, and express yourselves honestly and directly. This is what makes any relationship thrive, whether monogamous or polyamorous.
Good luck. You both have work to do, but it is not insurmountable.
Last edited by nycindie; 04-25-2012 at 10:48 PM.