She needs to have all the information to make a good decision though. If she asks you (or has asked you), I think you need to tell her how much you will miss her and your opinion. If you haven't there is also the remote chance that she things you won't miss her.

I'm not saying fall all over yourself and beg her not to leave, but tell her how you feel. Chances are, she knows how you feel. If you continue to bottle things up, it will affect your relationship. Level with her, that's my suggestion.

My husband and I discussed the idea of us living apart a lot before the decision was made. I knew he would miss me terribly (and me, him). However, I was not going to transfer to a new school, with new standards in my last year. It just made more sense for us to live apart.