As it turns out, weddings in the olden days sometimes followed kidnappings. It’s symbolic of the groom stealing away with his bride, whisking her away from her family and into a new life with him. The kidnapping theme also explains why the grooms carry their brides over the threshold in some cultures. In Medieval Europe, carrying a bride into their new home prevented her from seeming too enthusiastic about losing her virginity. By carrying her up and taking her into their home, the groom provided an alibi for his wife’s chastity.
It also appears that this custom also developed in other cultures for different reasons. Chief among these reasons was to thwart bad luck and evil spirits.