Completely understand your concern. We applied outland (Indonesian) and faced similar scrutiny from everyone (neighbors, employers, landlords....you name it). We had, what I would call, sketchy proof, no joint bank accounts, the house leased under the company name, etc. and our common law relationship was based primarily on time living together after I left Indonesia to work in Thailand. She had no visa for Thailand, but a multiple entry for Canada, so every 30 days she had to leave Thailand and return or we would travel back to Canada on my rotation. Our proof was primarily some pictures with family and friends (specifically the Canadian ones), 2 brief letters from the same friends and family and a huge file of travel itineraries, tickets and matching passport stamps. It was all good, so yours shouldn't be a problem.