How do I tell my son to tell his girlfriend it's time for her to move out?

About a year ago we relocated to a city about 40 miles from where we lived. There was no work up there so it was a wonderful move for us. My son's gf started staying the night a couple of nights a week, which was alright with us (he is 19 and has lived with her before). But about 2 months after we moved she came crying to me that her parents were kicking her out because she did not have a job (no work up there). So I said she could stay with us for a short time, get a job, and then move out on her own. Well, she got a job, but her stay seems rather permanent. How do I get her to leave without offending my son?