(CBS) What's the secret to a long and healthy relationship? Researchers from the Kinsey Institute at Indiana University in Bloomington say cuddling might be key - for men, anyway.
The researchers studied more than 1,000 heterosexual couples from the U.S., Brazil, Germany, Japan, and Spain who were in relationships for an average of 25 years. The study's participants, who were between the ages of 40 and 70, filled out a gender-specific questionnaire on sex and relationship-related topics that the researchers assured them would not be shared with their partner.
One stereotype-shattering result - that men may not want to share with their partners - was that frequent kissing or cuddling predicted relationship happiness for men - but not for women.
Other surprising findings include men were more likely to say they were happy in their relationship than women, and men said it was important that their partners experienced an orgasm during sex.
"We know from other research that being in a long-term relationship has some value to health," study author Dr. Julia Heiman, director of The Kinsey Institute said in a written statement. "Perhaps we can learn more about what makes relationships both sustainable and happy."
While men were more likely to report their happiness, women were more apt to report their sexual satisfaction - but significantly more so if they've been in a relationship for 15 years.
"Possibly, women become more satisfied over time because their expectations change, or life changes with the children grown," Heilman said. "On the other hand, those who weren't so happy sexually might not be married so long."
Which countries boast the happiest and most sexually satisfied couples?
The study found Japanese couples were significantly happier with their relationships than American couples - who were happier than their counterparts from Brazil and Spain. When it comes to sex, the Japanese were more likely to report satisfaction than American couples - especially in men where Japanese men were 2.61 times more sexually satisfied than their American counterparts.
"We recognize that relationship satisfaction and sexual satisfaction may not be the same thing for all couples, and in all cultures," Heiman said in the statement. "Our next step is to understand how one person's health, physical affection and sexual experiences relate to the relationship happiness or sexual satisfaction of his or her partner."