What if your very first girlfriend suggested you stop using condoms because you were “monogamous”—but she had about a million guys in her past and maybe more on the side? That was the predicament facing a certain State University of New York at Buffalo junior we spoke to (and won’t name in case the now ex-girlfriend reads this). In the end, the girlfriend literally charmed his pants off with the classic, “You trust me, don’t you?”

Science can’t hope to decipher the hormone-charged decision-making processes of young people contemplating sex. But a new study of 15- to 21-year-olds by the Bradley/Hasbro Children’s Research Center in Providence, Rhode Island, suggests that youthful confusion about relationship status can further muddy the waters.

“We’re really concerned about the misconception of not needing to use a condom in a monogamous relationship,” says Celia Lescano, PhD, lead author of the study, “Condom Use with ‘Casual’ and ‘Main’ Partners: What’s in a Name?” “Adolescent relationships are often transient. They might be deeply in love with each other one month and the next month they can be broken up and moved onto the next partner.”

Researchers interviewed 1316 young people in Providence, Atlanta and Miami and found 47% using condoms in no-strings-attached relationships and just 37% using them with a main squeeze. The low numbers are attributed to a mix of misinformation, inexperience, relatively brief relationships and substance abuse—and are unquestionably linked to high rates of HIV and other sexually transmitted infections. If only there were the same kind of agreement on what to do about the problem.

Health educators like Lescano argue that young people need relationship guidance alongside the scientific information they pick up in sex ed. Joshua Dickinson, 17, an editor of the for-teens-by-teens magazine Sex, Etc., agrees. “There’s a difference between being informed and being ready,” he says. “Good sex education shows you that you have choices.”

Teen-style couples counseling doesn’t make the grade in Steven Cohen’s classroom, however, and neither do condoms. He teaches an abstinence-based health curriculum at Classical High School in Providence, some of whose students participated in the study. “I emphasize the consequences of sexual relationships,” says Cohen. “The behavior is high-risk and unsafe.”

Neither side in this debate can claim much success at removing the “blinders” of young love. But then neither can that Buffalo junior. “I wasn’t fully comfortable with unprotected sex for a long time in my relationship,” he says of his ex. “But I started to have more faith in her, trust her and maybe even love her, I guess you could say.”