The young men in the study were more likely to have "mothers employed outside the home, fathers absent or dependent on the mother's income, or a child of divorce" than past generations, Simon says.
This may be at the heart of why young men today may be more sensitive to the trials of a relationship, she says.
Alternatively, Frances Cohen Praver, an author and psychologist in Locust Valley, New York, says the gender difference might be because women are less sensitive to these issues today.
"Women are more autonomous and independent. They need to love and be loved, but they can get love from their friends and family," she says.
This might also be why men in the study benefited more from the support of a healthy romantic relationship -- because they were getting support they otherwise wouldn't get.
But the issue cannot be explained by the social support element alone, Simon warns. "We can't tease out whether it's their emotional development at this time in their life, or if it's this generation, or what," she says.
So as for what causes these emotional gender differences, "That's the million dollar question," she says.