Divorce

It is estimated that between 40% and 60% of new marriages will eventually end in divorce. After looking at some statistics, I've found that people in the U.S. divorce more than Europeans. I am wondering why divorce has gotten more common.
Although I am happy that divorce is more socially acceptable so that people who really need them can get them, I feel like people take marriages less seriously because divorce is always an option. I feel like that it's in our natures to become spoiled, and if we don't have to work hard, then we wont.

 We are also overindulgent in our natures. Few people ever stick to one person throughout their entire life. Many people often cheat because they cannot help themselves or end the relationship.

Question: Do you think that it's in our nature to bounce around between relationships or that we really can stick to one person?