According to a study by the Alabaman Policy Institute, the longer couples cohabited before marrying, the more likely they were to resort to heated arguments, hitting, and throwing objects when conflicts arose in their subsequent marriage. A longer length of cohabitation was linked to a greater frequency of heated arguments, even when controlling for spouses' age.

Source: "Effects of Cohabitation Length on Personal and Relational Well Being" Hill, John R. Evans, Sharon G. Alabama Policy Institute Vol. API Study, Number . August, 2006. Page(s) 1-13.

(HT: FamilyFacts.org)