i am sorry you are going through this. it sounds like she may be afriad that things will turn bad.
my relationship with ex as as good as you described yours and just like you she broke up with me over the phone after 1.5 happy years. after we broke up i asked her how she would grade our relationship and she said she would give it an "A-" in terms of goodness and happyness. thats 85-90%
my counselor has been trying to explain the logic of why people end good things and why they do it in a bad way. and it your case the answer is much clearer than it was for me. in both cases i would say the motivation is her fear. plain and simple. yes she said she would move wiht you, my ex too said lots of things i later realized she didnt mean. there is nothing you can do about it.
even though for you 1 month is enough time, it looks like for her its not. i would say not to contact her anymore (and it sounds like you dont plan too). her motivation is her fear that something will go wrong. and like the self fulling profiecy that has lead to ending something good, in a not good way, and leading to things going wrong.
it just sucks. love you self and harm none and you will be ok