Helen Fisher, an anthropologist, has found that divorce worldwide occurs most common in the fourth year of marriage or between ages 25 and 29. She speculates that 4 years have been needed in human history to attract a mate, establish a home, produce a child, and raise it until it was weaned. Humans may have survived a few million years by changing partners with each new child or every 4 or 5 years. She suggests it could be our genetic inheritance. More than a million people a year get a divorce.
Divorce is most common among couples who have been married only two or three years.
For three decades the most common estimate has been that one out of every two marriages will end in divorce. The US divorce rate, highest by far in the world, was thought by some to have stopped rising in the 1980's but that was misinformation. There are many complex factors involved in divorce. Being pregnant when married increases the chances of divorce. Children of divorced parents are more divorce-prone.