'Taken for granted' is a vague phrase with a lot of meaning behind it. The first paragraph of this I think explains it best....

"Taking someone for granted means not cherishing the things someone does for you...it means expecting everything from someone and not giving the same in return...it means never being satisfied with what one has and what one is offered and constantly wanting 'something else'...it means not appreciating a person for who they are...it means wanting them to be someone else...and unfortunately, more often than not, people don't even realize when they are taking something [or someone] for granted...at least not until its too late [pushing someone away b/c of demanding all the time and it begins to harm the person or loss through other reasons such as illness or death, realizing then what was so special in their lives and didn't appreciate at the time, not until that person is gone.]"
Taken from: http://www.jason1365.com/2001/12/25/taken-for-granted/

Hope this helps.