Use our I130 affidavit sample and tips to create a strong affidavit for your spouse. Include these key points and avoid common mistakes.Much confusion surrounds the need to submit I751 affidavits and how to write them. We explain and provide an I-751 affidavit sample. We are thinking of submitting some proof of bona fide marriage. Can anyone recommend a good witness affidavit template that we could use? A simple letter of some sort where you write your name and details stating that their relationship is for real should be enough. 1. Talk to the person immigrating to the US. The person for whom you write an affidavit should be someone you know very well. To support a I751 petition and show that the marriage is "bona fide," couples must submit evidence that helps establish that the marriage is genuine.