The study published in the Journal of Family Psychology, reveals that couples who wait until marriage to have sex are much happier with the quality of their relationship.

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Couples were 22% happier and satisfied in their marriage if they had waited until marriage to enjoy physical intimacy. Even the couples who merely slept with each other without sex were not as benefitted in their relationship as couples who waited to take the marriage vows before getting physically intimate.
According to Dean Busby, a professor at Brigham Young University, when couples wait until marriage to have sex, they allow each other ample time and space to understand each other better. “Regardless of religiosity, waiting helps the relationship form better communication processes, and these help improve long-term stability and relationship satisfaction,” Busby said.
Source-Medindia