This happened to my friend and me too. We used to be close, saw each other at least 2-3 times a month. Our kids adored each other.
She moved away, and she stopped returning my calls. She even came to visit her parents here in town, stayed for a month, and didn't call me. Maybe she never saw me as a friend? I don't know. I still don't know.
It does hurt when someone you love just leaves you hanging. Without an explanation. It just putters out. It makes me sad still.
I am sad that it happened (ending of a friendship). But she is free to choose her friends (and choose who is not her friend). And if she ever contacts me, I will do my best to keep my heart open.
Easier said than done though. But I'd like to think I will choose to respond with love.