Even the title of this thread is full of wrong:
How to make a guy stop stringing you along?
How does one MAKE anyone do anything?
You cant! That person has to want to change!
YOU are the only one you have control over in life so grow a spine and move on.
You may want to ask yourself what exactly it is that makes you run back to the comfort of this dysfunction, over and over again.
Fear of abandonment maybe?
Its certainly not healthy behavior and you need to change it now or you will have a lifetime of dysfunctional relationships ahead of you.