I'm hoping to write something about that in the not too distant future. It does seem outdated in many ways, but then there are LGBTQ people who fought long and hard for the right to marry (and not just have a civil union). There's still an awful lot of cultural baggage tied up in the instituion of marriage despite all the ways that it seems to be on the decline.

My friend who lives in Quebec says marriage is rare there as well. People live together and have children but almost never formalize it.