March 6, 2000 (Reno, Nev.) -- In the 1955 movie "The Seven Year Itch," Marilyn Monroe tempts her neighbor to stray while his wife and children are away for the summer. Ever since, the seven year itch -- a period of restless angst -- has been used as an excuse for infidelity.

Now, a study suggests that such an itch is often a reality. An evaluation of 93 married couples during their first 10 years of marriage showed two typical periods of decline. (A decline was defined as a decrease in marital quality measured by taking into account passion, satisfaction with the relationship, amount of shared activity, and agreement between the partners.) The marriages started with a bang (with passion usually high), but after the "honeymoon effect" wore off they showed a decrease in overall quality over the first four years. The marriages then tended to stabilize before another decline set in around year eight, says Lawrence A. Kurdek, Ph.D., the study's author and a psychologist at Wright State University in Dayton, Ohio.

The first decline, Kurdek says, is probably a normal adjustment to new roles; the second decline is often related to the birth of children. Couples experiencing the seven year itch disagree with each other more, become less affectionate, share fewer activities, and express overall dissatisfaction with their marriages, says Kurdek, whose study was published in the September 1999 issue of the journal Developmental Psychology.

Why Seven Years?

The seven-year mark is coincidental, says Kurdek.

But it's not uncommon for problems to come to a head in a marriage after seven years, says Lonnie Barbach, Ph.D., a couples' therapist in Mill Valley, Calif.

Such was the case for Susan Fitzpatrick of San Diego, Calif. Not long before her divorce, she had returned to college full-time and took her first vacation alone, both of which were signs of growing independence that she says rattled her husband. He struck up an affair after eight years of marriage. She blames their divorce on a lack of communication and her husband's resistance to change. "He suddenly realized he wasn't happy about certain things in the relationship, but he wouldn't tell me, even if I asked," she says.

Statistics support the idea of a seven year itch. According to the most current figures available from the National Center for Health Statistics, the median duration of marriage was 7.2 years for couples who divorced in 1989 and 1990.

Singles and the Seven Year Itch

It's difficult to say if the seven year itch applies to unmarried people in long-term relationships, because the research has not been done. Sometimes, however, avoiding the "I do" helps keep the courtship alive in a long-term relationship, says Barbach.

But don't count on it. "I certainly wouldn't recommend two unmarried people live together to keep the romance alive," says Howard Markman, Ph.D., a marital counselor at the University of Denver, Colorado. "People thrive on a commitment in relationships."