Identify yourself and explain your relationship to the couple. Include anecdotes that demonstrate the authenticity of the marriage.Marriage Witness Affidavit Template: A Complete Guide for 2024. An Affidavit of Marriage requires information about the individual's name, their spouse, the date and place they were married, and job title. An effective affidavit for a marriage-based green card should provide detailed, truthful, and specific information about your marriage relationship. Learn how to complete a marriage affidavit template with our stepbystep guide for newlyweds.