I think a woman convinced you of this so she could ditch you without too much legal headache.
A friend of a friend of mine. He owns a house and had his girlfriend and her kid move in. Now she doesn't like him anymore, she has affairs and the kid treats him like shit too. They still live in his house, and being his common law, she could take half his shit and probably will to support herself and rotten kid. Dream come true.
The same thing generally applies in Sweden too, but we differentiate between common property in a relationship (such as house etc.) and private property. Marriage takes private property into account as well to a certain degree.
A quick googling tells me that there seems to be at least some tax benefits to getting married in Canada?