Marriage, under the law, is a contract in which two individuals agree to share certain obligations and liabilities, a mechanism that allows a "partnership"--insurance is a contract in which a third party, for a financial consideration, agrees to guarantee certain specified liabilities--in this case, certain defined healthcare needs--without a marriage contract, there is no legal obligation for the insurer to assume--the "domestic partner" is that there is an desire to share legal obligations and liabilities, but no legal mechanism to facilitate it--technically, there would have to be some sort of proof of intent, such as, in the concept of common-law marriage, shared residence for a given period of time.

The legal arguement for marriage is that these things can be established pro forma, by simple taking what amounts to an oath, rather than establishing them de facto, which is to say, by looking to see if people share a bed, share food, share expenses, in a manner with consistant with an implied mutual agreement--

This all seems like a lot of silliness to some people, and, at least as long as everything is abstract, it may be. However, I had a friend who was the longtime companion of a very successful executive who died suddenly--the family stepped in and, he suddenly found himself out in the street--(am I rambling again? Sorry--)