I'm sure that once your SO starts applying to schools and getting acceptances, you'll have a strong gut feeling about what you want to do. A year ago my SO (of 3+ years) got a tenure-track position across the country from where we were both living. I had been planning to wait a year before moving out with him, but as soon as I heard the news I realized that I wouldn't be happy without moving too. Now I'm applying to PhD programs, but only ones that are in the area (I lucked out that there are a lot of great programs close by). We'll be in another crossroads in ~4 years when he's up for tenure and I'm on the job market. Even though I'm neurotic about almost everything, I'm not really worried by it. There are a lot of opportunities like post-doc, non-tenure track, and lecturing that can give more flexibility in where we end up. Plus, it's great incentive to be the best grad student I can be; it ultimately makes life a lot easier if you have a lot of job offer choices.