Marriage in this country is sanctimonious. Many other governments actually require separate ceremonies wherein the wedding is for symbolism only and does not confirm any legal status.
I agree with you, and would even be willing to extend the abstraction further: An adult picks an "important party" that is their legal representation. By default, this is your Guardian until 18, after that pick someone - *Any adult*. This scares people because it sounds random, but it is just as random as picking someone to marry. I argue that the selection may be more, uh, rational. It could be the person you are "married to" (religiously) and I would image that would be the common case. I can see many of the legal benefits that are bestowed on a spouse as useful to give to someone else. I feel that requiring marriage to confer those rights to someone else "discriminates" against those that wish to remain single. For example, I am married, but if my wife should die, I should be able to confer these benefits upon my friend since the age of three If I desire. It's a matter of trust, not marriage, not emotion.
This abstraction could be useful for other issues such as mental illness where the guardian, or the state, could remain the "important party". Unlike today that requires More Laws And Paperwork to allow this to workout.
PS I've yet to figure out what to call myself. I'm typically cast into the "liberal" category by those more "conservative" than my self. Then again I'm fiscally Conservative. Not sure if you were trying to knock "liberals" but I agreed with everything else you were saying.