Monogamy itself is not a lie, it is a lifestyle. It is 100% choice and not forced on anyone. Yes it is encouraged in today's society, but by the same media that encourages cheating and divorce. The average consumer does what they are told to do. The only way to break free of this is to think for yourself, and be honest about it.
The lie is when you claim monogamy but are not happy with that choice. I believe in monogamy and am happy with that choice. My boyfriend does not believe in monogamy, it is not his first choice. We enjoy each other immensely but we are both aware that it is not a permanent solution to our difference in ideals. His happiness and his values are as important as mine and although he has chosen monogamy for right now, I don't expect him to keep with it for the rest of his life.
Honest monogamy... its a thing.. and so is honest polyamory... whatever you are, you are the one that chooses to make it honest or not.