Are your refering the letter about how you met? If so, I don't believe there can be too much information, once its useful information, it can never be to much. Recreate how you met each other. I wrote two pages (yes it was long ). I spoke about who introduced us and our frequent conversation before we actually met, I even spoke about the day we met etc. Remember you are convincing them that your relationship is real so don't hold back the information. Once its good information, tell the story.No I'm still gathering the documents.
I'm not sure how much to put into the letter, what is too much information?