My girlfriend of nearly 4 years recently told me that she only expects we have a few years left before we are separated by graduate school. Effectively, she set an end-date for our relationship. This is someone that I have loved deeply for years, and as much as I repeat to myself "impermanence," "life is suffering," I'm having difficulty coping with a sudden rush of sadness.

Does anyone have any advice on dealing with these difficulties from a practice/sutra perspective?

I'm struggling to "be with her" for every moment we have left together.