I missed this forum post. I do have a few thoughts on it though.
I chatted about this very topic with my wife, Pam, when we decided to marry – and the main reason to marry was to make the entire immigration process much smoother than the alternative of co-habiting. You wouldn't believe the difference, it's quite amazing.
So even Government (well, the Aussie one anyway) views marriage as a more stable and secure environment than co-habitation. With this in mind, that flows over into society and therefore a large degree of the population are going to be snared into the same belief. And I'd have to agree too. When I initially think of marriage and ‘living together', I certainly have the mindset that marriage is the more secure of the two. And that's knowing full well that legally as well as personally, both are just as easy to pull out of, providing the co-habitation period is greater than, I think, 18 months. 18 months, I think, is the period that the Aussie Govt views 2 people as in the same relationship as a married couple.
Hope that makes some sense.
Anyone else have a view on this?