Newlyweds could once expect at least seven years before the rot set in. But research suggests that many couples are feeling a five-year itch.
Scientists have discovered that couples begin to grow fed up with each other after just four years and are at peak risk of divorcejust before their fifth anniversary.
Researchers in the US, Russia and Scandinavia investigating the longevity of relationships found that the "honeymoon period" lasts for less than five years, with most divorces likely to happen between five and 10 years into the marriage.
If couples get through this patch, then the chances are they'll stay together indefinitely. As people become more affluent, the cost of splitting up can be a powerful factor in keeping couples together.
"One of the explanations for these changes in divorce risk is that during the first decade of marriage both partners go through crucial life-course transitions and challenging experiences - completion of education, building a career, bearing children, and so on," said one of the lead researchers, Aiva Jasilioniene, in a working paper from the Max Planck Institute in Germany.
"During the later years, the couple have developed strategies to deal with problems as they arise."
The report also shows that couples who marry young and those living in urban areas are more likely to divorce; tying the knot at an older age contributes to marital stability.
