a young marriage in trouble

[Mozza]

Yes, you can recover, we always can, but learn the lessons.

One of them is: Don't call with the intention of teaching her anything. In your case, I'd add: Don't call if it can be avoided. With my W, this kind of exchange comes down to 2 texts or emails: "Can you take D3 and D6 tomorrow?" and "Sorry I can't / Sure I will". Perhaps some logistics afterwards.

Just accepting to take care of him would have sent the signal that she needs to be more flexible. Speak with your actions.