My SO and I also discussed this dilemma. We came to the conclusion that he couldn't possibly leave to come with me, and that we also would have a very hard time with the long distance (cross-country) relationship. So we decided that if I have to go, we would try it, but wouldn't expect it to work, and wouldn't have hard feelings, so we would stay friends. And if we were both single when I finished the PhD, we would try to pick it up again. My decision was eventually made easier by rejections from the schools in my current city But the bottom line for me in the decision making was that I was going to give away 5+ years of my life for something that would change my life and open a lot of opportunities for me, and for which there is no substitute. And unless you are ready right now to settle with your boyfriend and start a family/spend your life with him, the rest of your life should trump this relationship. All personal opinion, of course