(Fortune Magazine) -- We made it through the bursting of the Internet bubble and now the bursting of the real estate bubble. Next we may be approaching the end of the most worrisome bubble of all: the standard-of-living bubble.

That conclusion comes from the latest data on credit card debt. It's growing fast, but the problem is bigger than that - and to understand what it means, we have to take a few steps back.

For the past several years, the average inflation-adjusted total pay of American workers hasn't been increasing. That means we haven't been building a foundation for increases in our living standard. You might be tempted to say that by definition our living standard couldn't have increased, but that's not quite right. Even with stagnant real incomes, we can always live a little better every year through borrowing and pretending that our living standard is still rising, just as it was for decades.

So the Great Bull Market made us feel rich, and we felt justified in saving less and borrowing - and spending - more.

After stocks collapsed, home prices took off, making us feel rich all over again. So we continued saving less and spending more, creating the illusion that our living standard was still rising. In 2005 our personal savings rate went negative, but even that didn't slow us down, because our homes were still appreciating - and rising home values meant that household net worths weren't declining. (Don't be fooled by that saving-rate spike in this year's second quarter; it was probably a one-time event resulting from the federal stimulus payments.)

Of course, we don't hear those assurances anymore. Stocks are back where they were eight years ago, and home prices are where they were five years ago. But personal debt is much higher than ever before, and average pay is still going nowhere in real terms. So now how do we live as if our living standard is still rising?

End of easy money

That's where the credit card reports come in. Last year, just as the subprime crisis happened, credit card debt took off. The home-equity ATM had been shut down, so people turned to the last source of easy money they had left, the most expensive debt on the menu, credit card borrowing.

Since credit card debt has been growing much faster than the economy - more than 8% in last year's third and fourth quarters and over 7% in May (the most recent month reported)- people are apparently using it as a substitute for income. Thus, for the past year or so we have still maintained the standard-of-living illusion.

But a big crunch is coming - and here's why. Credit card debt, like mortgage debt, gets bundled, securitized, and sold off by banks. Citigroup (C, Fortune 500), one of America's largest credit card lenders, just reported that it lost $176 million in the second quarter through securitizing such debt. That happens when the buyers of those securities observe rising delinquency rates and rising interest rates, and decide the debt is worth less than Citi thought. More generally, the amount of credit card debt that is securitized nationwide has plunged by more than half in the past five months because it's getting riskier. That means credit card issuers will be charging customers higher interest rates, and since the banks can't offload as much of the debt as before, they'll have less money to lend to cardholders.

The squeeze has already started, which is why Congress is in the process of passing the Credit Cardholders' Bill of Rights, which would prevent issuers from changing rates and terms without warning, among many other provisions. But bottom line, the credit card money window is going to start closing - and soon.

So now what? It's hard to see where consumers can turn next. Home prices seem highly unlikely to start rising again soon. Stocks? You never know, but the Great Bull Market looks like a once-in-a-lifetime event. Homes and stocks are households' biggest asset classes by far. There isn't much else to borrow against.

It may be that the standard-of-living bubble finally has to deflate. Sustainable increases in living standards have to be earned, not borrowed, and that means performing ever higher value work that can't be outsourced. We haven't been meeting that challenge very well; doing so will probably require much more and better education for millions of Americans, which takes time and money.

The result may feel like deprivation, but I don't see it that way. Who knows - we might even find that living within our means and saving a little money actually isn't so bad.