It sounds like she just doesn't care any more.
She didn't bother to say more than a few words, and didn't call you when she said she would. Things may come up, people forget. But if she really cared, she would have called to at least say more than a few words before her trip where she wouldn't even get to talk to you.
Like it was said before, this may be just a stage. But it sounds like the relationship is about as close to being over, without it being official. You could try to salvage it by having that talk with her, but it may not work.