Hello Andy14.  I am so sorry about your girlfriend.  I was diagnosed with cancer 5 years ago and it broke my marriage up.  I left my husband and went to live with a relative because I didn't want to ruin my husband's life.  In fact, I told him to move on without me and  try to meet someone else.  Perhaps your girlfriend is thinking along the same lines?  Being diagnosed with cancer (especially stage 4 cancer) throws us in to a tail-spin and we make decisions that might seem very odd to other people, but to the person with stage 4 cancer, it makes perfect sense.  Also, it could be that your girlfriend is trying to process everything and she simply needs some time to herself.  You say your attempts to reach out are ignored, so perhaps you could write her a letter and tell her that you are still here for her if she needs you.   Give her the space she needs, and hopefully she will contact you at some point.  Good luck to both of you.