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A large age difference is only one factor that is considered when USCIS is adjudicating a petition or the consulate is issuing a visa. It is a flag. Another flag is when there is no common language between the spouses.
It makes a difference whether you are applying for a fiance visa or spousal visa.
Also it makes a difference if you are doing consular processing or adjustment of status in the US.
Why? Because if adjusting status in the US you are able to live together and create a stronger case of a good faith marriage by establishing joint accounts and comingling your lives.
For example if your spouse is here in US you can gather documentary evidence such as the below examples
Any types of documents that have both your names on them that show that you bought a car, a house, furniture, or anything else together.
Any rental or lease agreements for your home or apartment with both of your names on it or a letter from the building manager or owner proving that you lived together.
Bank or financial statements that show that you had or have a savings or checking account together.
Any insurance documents that show that you were or still are covered by your spouse's insurance plan, or that your plan covers or covered him or her.
Bills, such as electricity, water, heat, cable TV, phone, or others that show both you and your spouse's names.
Jointly-filed Income tax papers (both your names).
An identification card that shows that you use your spouse's last name.
Membership cards for video clubs, grocery stores or similar businesses, that show joint membership.
Are you married?
Is your spouse here in the US?