How about car insurance? Phone bill? Health insurance?I sent out a letter of explanation, I sent out etransfer receipts from that time and they were pretty frequent as we didn’t have a joint account until almost 10-11 months after we moved in. I can definitely send more letters from friends and family. And I am unable to get in touch with my previous landlord and when I asked him to write me a letter he refused to be involved at all. Well, the only thing is that my boyfriend owns a house with his family and so he didn’t change his address on any documents and mails until we got our new place together. So basically I don’t have much proof other than etransfer receipts showing that we shared financial responsibilities.
TBH you really don’t have much proof to show. You should have gathered more proof before applying or get married.