One would think that rationally, fewer young men than women would naturally lead to proportionately more young men getting married, but that’s not the case.

“Marriage patterns aren’t rational because men and women have somewhat different reproductive strategies,” Kruger said. “Men have a greater reproductive benefit than women from having a greater quantity of relationships. If they can leverage their scarcity into attracting multiple short-term partners, they will not have as much of an incentive to settle down.”