Standard, no. But it happens and don't worry about that. If they would have real doubts about your cohabitation, you would not already have DM.
Possible proofs:
- lease or mortgage showing both names
- driving licence showing the same address
- governmental letters showing the same address (like notice of assessment from Canada revenue agency, letters from your province health insurance program,...)
- utility bills (electricity, internet, phone,...) showing the same address
- ...
One or many proofs? I'm always feeling better being on the safe side, so I would say bring many of them, but one (if they even look at it) should be enough.