So, assuming that $90,000 + $21,000 is actually take-home pay, they're spending $56,400 a year just on rent and child care, or a tad over 50% of their total household income, just for a tiny cubbyhole and the must-be-fabulous-to-be-worth-the-net-loss benefits package on her job. That's an incredibly shitty allocation which precludes saving, and considering the prices in metro NYC, they'd have to be practically camping in that place and completely reliant on public transportation (Which adds up to a pretty considerable expense itself, over the course of a year, if you have to use it for everything, and also subtly restricts where and when one travels).
Of course, if that's gross pay and not take-home pay, with Federal and NY State income tax and NYC's additional income tax, they're just plain screwed, and living out a losing proposition.