What inflationary two check tipping point? What are you talking about? That’s not how inflation works.
When over half of the formerly one wage-earner households had two incomes, the price of housing, vehicles, and dangnear everything else went up. While there was a gap in there when people could afford more stuff, it didn't last. There was more money in the economy, and it became worth less. The wages which would have sustained a household just didn't get the same at the store and it became more difficult to get by on just one paycheck.
That is inflation.