Why one would complain over something that they themself do it as well?

He always reply me late or sometimes just ignore my text totally. I always tell him that i dislike when he did that, but oh well no changes. So now i do the same to him, but when i did that to him, he would start to question why and bla3. My answer is always easy "i just do what u did to me"

Its dang annoying

Why one would complain over something that they themself do it as well?
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