FYI continues its spotlight of marriage in America (“Arranged,” “Married at First Sight,” “Seven Year Switch”) by documenting couples’ leaps of love from teen sweethearts to married couples. The series’ hourlong episodes capture their weddings and all the ups and downs of juggling family, school, career, finances and first homes, while still navigating teenage lives. Universal life stages are explored as viewers watch the newlyweds work through issues most American couples tackle when they are older and wiser.