G Sharp

I guess what you're really trying to say is that a couple enjoys many of the legal and domestic benefits of marriage already, why get married?

Good point but not entirely accurate. Child support does not require the parents' marriage as a condition. Many courts allow contractual agreements between the unmarried partners to allocate property [Lee Marvin case]. You can will your property to your girlfriend if you die, etc etc. So what other rights are there that marriage gives?

Actually, quite a few signifcant ones. One major benefit is if a spouse dies, the law recognizes the relationship as conferring death/insurance or other benefits to the surviving partner. There is no similar right in "long term girlfriend" situations. If a partner gets in an accident, the law allows for "loss of consortium" to the surviving spouse but not to an unmarried partner. Although some states are beginning to move away from this law, this is still the general pattern.

Finally, the largest benefit of marriage is actually social and symbolic. It is a pronouncement to the community of your mutual commitment--it ties in to tradition and, to some, religious tradition.