If you know someone treats you like Moon,Calls you the Moon of their life and still you treat them like dark, dont consider them as a part and proves them the wrong always,
than i will just suggest you to tell them that "I dont feel the same and cant consider you the same" and i can assure you that he/she wont even have the second thought and may wont look at you in all their life,all they are waiting for this sentence to be told directly to them on their Face.
Because they already know this thing,they just want to be told and yes if a person who replies you within seconds after getting reply after an hour can be the person who wont even text you or even Block you.
Just a thought.