monogamy vs. loyalty

It seems to me that society is beginning to call in to question the importance of monogamy, suggesting it is an outdated norm requring something of which the human race is incapable.
Many are ready to throw the entire concept out the window; I must have read 5 articles in the last year regarding the acceptance by Europeans that husbands and wives cheat, suggesting that we as Americans are somehow lesser-evolved because we require it of our marriages.
But.
Why are we ready to ditch monogamy, to write it off as an unrealistic ideal yet we continue to so highly value loyalty between any and all other relationships? We feel betrayed by the fall of the big banks of Wall Street, with their golden parachute CEOs who knowingly entered into high risk situations only to have our hard-earned tax dollars bail them out as we sit having our homes foreclosed upon. We expect those people - people we have never personally met - to be personally responsible with our investments/properties/markets. But we should not expect even the decency of a one-on-one intimate relationship from a partner whose nuiances we can read through years of love and commitment?
What is the justification for allowing a spouse to voilate your trust but expecting your employee not to embezzle millions?