People who don't respect boundaries?

Why do people constantly try to push boundaries when you lay them down?

Say for instance when I say no I don't want do something why do they keep asking me over & over. Why isn't one no enough even if I'm being assertive. It's tiresome and pretty hurtful when I respect others personal boundaries but when mine come in they keep trying to test them? Why do this?
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+1 y
*Why isn't one time not enough even
People who don't respect boundaries?
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