If one person is drawing a paycheck and another is supporting them in that role, then the supporter is putting in a ton of resources, but if the marriage ends, the breadwinner owns the entire "career". So the breadwinner reaps the long term benefits of the career, and the supporter loses everything but whatever skills they gained.

For the supporter, the advantage of legal marriage—where the supporter owns half the assets plus some rights to future earnings—is obvious. Smart, capable supporters know this, and won't make that investment without legal protections. Anything else would be reckless.

The advantage to the breadwinner is that this is a way to get a smart, capable supporter. If you're not willing to provide the legal protections, you're just going to get someone who doesn't really understand the situation and doesn't understand the risks. There's some chance you could find someone who was generally capable, but who was naïve on this point, but that's a smaller dating pool. And I'd argue it's ethically wrong, and the unfairness will eventually degrade the quality of the relationship.

People think alimony is just someone sucking someone dry while doing no work, but it's really just a dividend being paid out from a shared venture that you were both equal partners in.

If someone believed that they could attain a smart, capable supporter without offering those legal protections, however, then you agree that it would be rational for them not to provide those protections, right?

Not to mention the sizable portion of men who don't care about the intelligence/capability of their partner, or those who don't believe that wanting a legal upper hand correlates positively with the type of intelligence/capability that they desire.

To name a few: Joint filing of tax returns, Medicare, Social Security, immigration and residency for partners from other countries, sick leave to care for partner.

You can find more here:

http://lesbianlife.about.com/od/wedding/f/MarriageBenefit.ht...

It provides a different social perception too.

In your 20s its fine, put off getting married, but the 40 something guy who introduces you to his girlfriend sends a totally different signal than someone who introduces you to his wife (and vice versa if the genders are swapped). It says you're noncommittal, bad at relationships, maybe previously divorced, constantly shopping around, maybe breached partners trust repeatedly, whatever, take your pick. What it never says when someone is judging your book by its cover though is "this is just some guy who's been hedging against marital risk for a couple decades", any other snap judgement requires the person know you better.

Do you ask to see a copy of their marriage license whenever someone introduces you to their wife?

For tens of thousands of years, it was possible to marry someone without recognition from the US government. I suspect it still is.

The US government will help them take half your property after a breakup even without a marriage license, if they determine you were "acting married" so to speak.

It certainly is. We're never required to consult any of the colonies when we decide to marry.

Or, just maybe, you're happiest living in a way that's really no one else's business.

Jesus, it sounds so 1960s

That's a fair question. I think the biggest benefit would be the recognition of commitment, both by the partners, their families, coworkers, etc., zooming out ad infinitum. It can make a lot of things easier, from a practical perspective--for example, in my line of work there are a lot of couples (shared drive and passion, assortative mating), and employers will often create a second job for the spouse of a person they really want to hire. I think that sort of similar things can apply in other situations. If you, say, want to see your partner in the hospital or have certain other rights it's easier if you're legally bound to said partner.

See the recent arguments about same-sex marriage for a fulsome discussion...

I chose marriage, because I was really f'ing excited about calling my partner my wife. Now, I am really proud to call her that. Note that financially, she is far more well-off than me, but we have similar lifetime earnings potential. YMMV.

Edited: grammar.