Is there a way to add cost of living increases to that graph?

That’s what “real” means, it accounts for increased costs due to inflation.

If you’re worried that more income is being consumed by necessities, real disposable income is also on a steady upward trend:

https://fred.stlouisfed.org/series/A229RX0

And yet, people have moved from often single income households, to double income households, and still struggle to buy homes...

So there is a disconnect between those real/disposable income numbers and the actual market realities, no?

No. The “vanishing middle class” is a convenient political myth supported by anecdotes and misleading charts.

Most of the middle class that “vanished” became part of the upper classes, at least as they would have been defined in real economic terms a few decades ago. Look at college graduation rates, or # of workers above $100k comp (real, not nominal), or the net worth of retirees, or …

America is vastly richer than it was even in 1990. Those riches may be modestly less evenly distributed—though there are demographic forces at work there as well as raw economic ones—but the median American along any number of axes is much, much better off.