Although no one anticipates a separation or divorce upon entering a relationship, it's wise to have a plan in case something unforeseen occurs. Prenuptial, post nuptial and cohabitation agreements are particularly essential in second marriages and relationships, as well as in blended-family situations, where legal rules and responsibilities may not be well known. Learn about these different agreements and how they are used to determine the distribution of property and incomes at the end of a relationship.