From my point of view anyway (so it's not necessarily right), it seems like something isn't quite right in her life and caused her ending things abruptly that was seen. You deserve to know why she ended it though, cause from the way I see it, you did nothing wrong and adored her like no tomorrow.
If she doesn't give you an answer and/or is being mean about it, then she simply doesn't deserve you
I'm really sorry to hear this Odd Socks, I wish I could help in some way
You're too amazing to feel like this