> in most Western countries (including the U.S.) even living together binds you to the same or almost the same contract as marrying.

Correct. This is such a terrible thing. I'm coming up on 6th year of living with my girlfriend and I am told that California is also something like this... i.e. if you are living together for 7 or more years (maybe 10, not sure) that it's as if you are married. Terrible!

This is incorrect and is a common myth being propagated recently. States don't have a defined time period. It's up to the parties to make a claim in a court whether they are reasonably married (looking at correspondence, documents, etc.)

http://www.npr.org/2016/09/04/487825901/no-you-re-not-in-a-c...

How does this work with same sex roommates in states that allow same sex marriage? Or even simpler, what if a male and female live together as roommates?

I've never heard of this. Someone can actually be entitled to half of your wealth just for living with you...?

If you live together long enough. Common Law marriage or something...

Common law marriage is only a thing in eleven states. It requires the couple to present themselves as married.

Australia and Canada have common-law relationships that aren't marriage but do involve dividing property in courts.