I can also relate to this, I had a best friend for years as well, she shifted , and we kept in contact , seeing each other once a year maybe and writing letters, but each time I saw her I felt we had less in common, and the visits were becoming difficult for me,however I kept up the connection although really I knew it was doomed, I sent her a xmas card and never heard back, I am sad we have parted for many years now, and felt she could have at least written a letter saying how she felt, and I would have understood, as I was glad to end the friendship too really.

I often think of her to this day and wonder if she is ok,but I am still miffed that she ended it so cowardly.

Take the other's advice and play it cool, if she really wants to continue her friendship with you, she will make the effort, if not I am afraid you might just have to let it go.,sad as that maybe.