Wives and girlfriends -- for the sake of your sex life, you might not want to get too buddy-buddy with partner's friends.
A new study, published in the American Journal of Sociology, shows that when a woman becomes closer to her male partner's friends than the man is himself -- something called partner betweenness -- the man is 92 percent more likely to experience erectile dysfunction during sex. His ability to achieve orgasm also decreases, researchers said.
Researchers from Cornell University and the University of Chicago looked at data from 3,005 people aged 57 to 85, a third of whom had experienced erectile dysfunction.
But researchers found that the "partner betweenness" phenomenon was especially prevalent among men on the younger end of the age spectrum. As the men got older, though -- to their 70s and 80s -- the association disappeared, likely because older men take on a new attitude of masculinity, one of kinship and mentoring instead of independence, researchers said.
The problem lies not so much with jealousy, but that a man's sense of independence, privacy and ability to function on his own are disrupted, TIME reported.
When a woman steps in and usurps one of those close male bonds, she may threaten her partner's manhood and his sense of male identity, thereby increasing the likelihood of sexual dysfunction.
Most men do have more contact with their friends than their partners do, said study researcher Edward Laumann, of University of Chicago. But about 25 percent of men in the study did report experiencing partner betweenness, he said.
For those cases, "it might be a good idea [for women] to keep a safe distance," TIME reported.
Relationships aren't the only thing that impact erectile function -- new research also shows that weight loss could also improve erectile function and sex lives of obese men who have diabetes.
For more on what could be causing erectile dysfunction, and how to solve it, click here.