Hi...I don't know what they'll consider a simple case but I can give you some details about mine. So ..both of us were previous married and divorce, we know each other for almost 4 years, got married after 3 years. We provided pictures with all the trips that we had together..US California (visiting his parents), Santorini Greece (honeymoon), Romania, Canada, a lot of ppl from the wedding that was in Romania, including friends&family from Mexico and US. I think that with all this we proved that our relationship was genunine. And yes, like Irina said, I visited Canada before, as visitor, where I lived with my husband a few months before returning to Romania.
Another thing that it might matter...I was eligible to emigrate to Express Entry, on my own...idk if this matters or not, but maybe they are thinking that if i'm going then i'll actually produce something for Canada's Economy.
Good luck to everyone and if you still have questions ...i'm around.