Freinds no more

So, I'm posting from the other side as I have been the 'dumpee' in this situation.

In my case I didn't tell her the reason why in the initial "I don't think we can be friends" message as if I had done so felt like she would have felt like an attack on her (as I did have some issues with her character) so instead I worded it as if we had grown apart - no point in listing all the things 'wrong' with her as it seems unnecessarily hurtful and better to walk away just thinking she isn't MY person but may be someone else's. However, in her reply she didn't ask...at all. She didn't ask if she'd done anything wrong, if there was anything we could do to improve things etc. so I didn't give her any answers. Had she have asked though I would have been honest.

All I can say is there may be loads of reasons. She may be having issues with herself, she may have issues with you and doesn't want to hurt your feelings (or both). It's a very hard thing to be honest about so unfortunately you can't force her to tell you.

The only advice I would say is ask the question. If you've upset her and she doesn't tell you why/how then you can't fix it and that's not on you it's on her! Unfortunately for you it must be heartbreaking but at least you know you've asked.
I would probably end with saying something along the lines of you hope she's ok, as if there's something going on with her (nothing to do with you) then it may leave the door open for her to approach you and talk about it when ready as she may just be pushing you away as she's struggling to deal with her own stuff.

I hope that helps and I hope you get some closure x