Thomas is right. It is all part of the fabric of family life all around the world. Parents raise their children and the children grow up and move on with their lives as they should.
Sometimes that means crossing the globe to far flung places and only being able to keep in touch with your loved ones by phone, email etc. We all have people we care about who are not close (in person) to us but they know that we still care.
My father is only 73 and has Parkinsons Disease. He lives in Devon which in U.S. terms is not very far away but in travelling terms can take up 6 hours with heavy traffic etc. I try to get to see him as much as I can and also call him up each week to see how is.
Don't feel guilty - your parents have lived their lives and would wish you to live yours also.
Phone as often as you can and write to them.
Keep your chin up!