Given the context I think that this sentence means "it's probably an unintentional action". But I am unsure of what meaning/nuance the うち adds here. I am used to seeing うち meaning "while" and that's ...
I think the difference is mainly just a nuance: 毎・・・each ・・・それぞれの 各・・・every・・・すべての I think 毎 is used mainly with 名詞や動詞 「年毎に」 「会う人毎に」 Or there is any other difference?
Background: Yes, I have tried typing "cry" into Google Translate. Although, there are so many options, yet no example sentences for each word. In my case, I have been writing a compare & contrast ...