In our life we can't decide about many thing we do what we do sometimes we have to act against our wishes but than we have friends ,people around us and sometimes we can make thing different we can decide who we wants in our lives.if we like someone we want to spend time together do thing together so why in the world are those who show all the symptoms of dislike towards us but still keep us hanging on.why they don't live us alone are they feeding themselves with our pain

Not sure I read your question right, but if this is about people, ex'es or whatever, that keep stringing you along yet never have any real intention of being with you or being real friends, then I'm guessing the reason is quite simple.

Everyone wants to be liked. And everyone wants to be liked a lot. When someone treats you disrespectful, and like garbage, and you still keep clinging on to them and wanting them in your life, then obviously this person feels like he or she is very much liked because no matter how much of a doubhebag he/she is you keep coming back from more.

That would be my guess, anyway. Short version: it's all about ego.

Its very simple really, they do what you let them do.

Don't blame them!!

Tal is also right though.