She is doing this now because she needs space, but she very well could want you back once the dust settles and she isn't going through such a hard time. This is actually VERY common for suicide survivors to want out of romantic relationships after such a terrible occurrence. During the grieving process, people either go one of two ways, they cling to their partner, or they push them away entirely.

This is actually part of the grieving process.
She needs space because she can't handle it right now.

So tell her you understand and you'll always be there for her. Stay her friend. That way, in a few weeks or months when she's feeling better, she might want you back.