Can we talk about the financial reality of staying vs going back?

My wife wants to stay home. We have a 2yo and she's been WFH but wants to fully step back. Sounds amazing - less childcare costs, less stress, one person managing the household.

But here's the math: her salary is $78k. Daycare would be $15-18k/year (less than her salary but our high-deductible health plan requires two incomes for good rates). Her student loans are $200k.

Everyone says "oh just live on one income" but we'd be okay, not thriving. Am I being too practical? How do other couples navigate this when the numbers don't work out perfectly?