Originally Posted by trekr5
You have to focus and decide what is important to you. Your parents will always be there and your girlfriend, once you explain things to her, will be supportive as well.
Maybe that's a little off topic, but still:
I have made the experience that your parents will NOT always be there - and that if they die at a time when you have been postponing calling them, visting them or sending them a just-to-say-hello card you will really regret that you didn't do this earlier while you still had the chance to do it.
So my suggestion would be, that if you focus on your work and studies you should explain this not only to your girlfriend but also to your parents, to avoid giving them pain and straining your relationship. And to try making the most of the time you spend with them - get to know them while they're here.