This affidavit documents the cohabitation of two individuals for over ten years without being legally married. Discover an affidavit of cohabitation sample to simplify your legal process.A spouse of a US citizen must submit with the naturalization application an official civil record to establish that the marriage is legal and valid. Step 1 – Fill in the information of both parties. The first step in writing a cohabitation agreement is filling in the parties' information. Applicants who reside alone must fill out the bottom portion of this form but do not need to notarize it. You fill out a form. The document is created before your eyes as you respond to the questions. Axinn and Arland Thorton, "The Transformation in the Meaning of Marriage," in The Ties That. Attorney General in addition to the complete text of the law.