That would be my advice to vandalin. I would approach her and express that I'm feeling ______ about the way our relationship has changed. Derby, if you just want to cut ties then I agree with Mono. Let her come to you. Doesn't have to be more complicated than that. But, if you're feeling hurt and would like to work on it with her, let her know that you don't like plans being cancelled, etc. Is she approachable that way?
My heart is too big to fit into one person.