Since this is very intimate, do not tell her for sure because this kind of thing is for a face-to-face and you are four states apart. So logistically it is impossible and end of story. When you are face to face, you will then reassess the situation - by then a lot of changes might happen. She may or may not break up with the gf, you may or may not get your own partner, etc. - it is impossible to predict. So just write it off as currently impossible due to circumstances outside of your control.