Why is everyone cheating on each other? I think i know, but what do you think?

Why is it that on every message board on the internet, if there's a category about anything related to family, marriage or relationships, there are posts about cheating? Is there some crazy *** epidemic? Well, here's what I think...I think human beings are not, by nature, monogamous beings. I believe that society and organized religion drill into our heads that we're supposed to be with one person forever and if we have before or outside of our marriages, we're going to hell. Well here's where it gets fun...let's look at how that's working so far. 50% or better divorce rate, some polls say 70% or more people have cheated at least once, message boards and blogs and websites about cheating are everywhere...if we are truly supposed to be monogamous creatures, why the hell can't any of us seem to do it? Please let me know what you think.