Pretty difficult to prove a negative. You said you need to submit a affidavit/certificate. If an affidavit works, that is just a sworn statement. You could theoretically type a statement swearing under penalties of perjury that you’ve never been married and sign in the statement in the presence of a notary who signs to confirm you provided the statement.

In other words, you are looking for some magic document that probably doesn’t exist. Maybe try the simpler path.

Feel free to ignore me (you probably should). I’m not from Mass. I just follow this sub because I visited Boston last fall and liked it.

Edit: sorry for all the typos. I was working off my phone.