Good question, and a pretty comprehensive list.
I think most people want security, and what that security is differs according to person. For some that security is present in financial wellbeing, and for others it might be present in the image of a constant companion or even the comfort of having an elevated social standing after no longer being a bachelor. Sometimes children can be the glue that holds together a marriage. However, Barbey d'Aurevilly wrote as follows in Les Diaboliques.
"Are you not sorry not to have any children, Madame la Comtesse?"
"I do not want any,"she said proudly. "I should love Serlon less. Children," she added with a kind of scorn, "are good only for women who are unhappy."
However, don't think for a minute that everyone is content to remain with one woman for the rest of their life. Many of the best of husbands have mistresses! A decent amount of the population, in fact, causing florists are worried about the upcoming St. Valentine's day. A lot of the flowers bought are meant for mistresses and are often sent to their place of work. This year, St. Valentine's falls on a Saturday, when most people don't work, so these adulterous husbands are denied that option. They certainly can't send the gifts to their mistress's house, possibly alerting her family to the presence of this passionate paramour!
For some people, another partner keeps the novelty of marriage from fading. Whether I condone it or not is another question.
Remember, the people most offended by the Clinton scandal were Americans and British. Most other European nations saw it as fairly healthy. The French, I think, even expect public figures to have secret mistresses.
QUOTE
MARRIAGES DO SURVIVE:There are many examples of everlasting marriages.A large number of people in Europe and Australia have strong faith in marriage.In Asia most marriages last.But then why???????
THESE MARRIAGES MAY HAVE SURVIVED BECAUSE-
1.PARTNERS HAVE MORE LEISURE TIME TO INVEST ON MARRIAGE
2.PARTNERS ARE WILLING TO FORGIVE THE MISTAKES OF PARTNERS OUT OF LOVE OR OUT OF COMPASSION
3.FEAR THAT THEY MIGHT BREAK A GOD MADE RULE ON MARRIAGE
4.BECAUSE THEY WANT SOCIAL SECURITY AND RESPECT FROM SOCIETY(IN THE EAST)
5.THEIR LOVE IS UNTIRING
6.THEY WANT THEIR CHILDREN HAPPY
7.THEY HAVE FEWER EXPECTATIONS FROM MARRIAGE THAN MOST OTHERS
Are you asking here why marriage is more likely to last in places other than the U.S? I'm not sure. It may be that ennui that not only kills marriages, but reduces voters and makes citizens wallow in ignorance.