Since I'm digging a hole, I might as well make it nice and deep. I believe men and women are very different, we have different sex drives, we age differently due to hormones, we compliment eachother at times but the thought that we can live monogamously and be fine is insane!
If nature truly meant for men and women to grow old together in a monogamous relationship, I'm certain we would both experience a similar menopause. I know women are unfaithful, but compared to men they don't even come close.
Society keeps trying to domesticate man, he must suppress his instincts to be physical when threatened, he must suppress his sex drive and be faithful when married. I follow those ideals, but it's dam hard not to lash out at times and it is a constant effort to suppress a very powerful instinct to pursue other women.
I love and respect my wife, she has been good to me all these years and has been a wonderful mother to my children. I still think finding a good woman to share intimacy and life is magical. Having children is difficult, sometimes heartbreaking and sometimes very rewarding. Just don't tell me marriage itself is natural!