A new study that examined the concept of monogamy in young married couples found that for many, it's a 'complicated' issue.
"Couples have a hard time talking about these sorts of issues, and I would imagine for young people it's even more difficult," Live Science quoted Jocelyn Warren of Oregon State University as saying.
"Monogamy comes up quite a bit as a way to protect against sexually transmitted diseases. But you can see that agreement on whether one is monogamous or not is fraught with issues."
The study of 434 married and unmarried couples ages 18-25 revealed that about 40 percent of young couples had differing opinions about how exclusive their relationship was, and even among those who were on the same page, about 30 percent reported having cheated.
The only indicator of exclusivity was the emotional commitment the partners reported investing in the relationship, assessed using a scale from 1-5 with 5 being the highest.
Researcher Marie Harvey said that young couples in a monogamous relationship such as a marriage should be encouraged to have protected sex.
Even if the person says his or her partner is monogamous, the clinician "may want to think about advising that young person to use protection," Harvey said, since for many young adults, whether or not they know it, their relationship status remains: "It's complicated."
The study will be published in an issue of the Journal of Sex Research.