Going home to my SAHM DW and two DDs is like going to a foreign country sometimes - they have a different language and they do things differently. But unlike a foreigner I don't seem to get a margin of appreciation.
DW really puts the boot in when I do something wrong (e.g. fail to notice when a nappy needs changing or use the wrong milk), but when she does something wrong (e.g. food too hot for DD1), it's totally excusable because she's too tired, distracted or has too much on her mind.
I acknowledge she might want to be defensive about it because she's their primary carer and doesn't want to be being seen to get it wrong, but we're both only human - she's gone through the learning curve and I need to as well.