Getting Back to my Old Self

[Coconut]

Is this just her and this level of casual is just all she is capable of? If it's the last one, I need to adjust my response.

I vote this one, you understandably have expectations from her due to the length you all have been seeing each other, but expectations have never been discussed much less agreed upon (has she ever actually even said ya'll are/were dating?).

Personally, I agree with backing off, I would keep some communication going (maybe a text every 2 or 3 weeks) just to keep communication channels open, I wouldn't mention the cruise until one of two things happen:
1. You have to know she isn't going so you can notify promoter (even if you don't have a replacement)
2. You want to replace her with someone else regardless of if she wants to go or not

I know you feel differently about her, but maybe change the mindset more towards booty call type relationship unless her actions start matching more closely your expectations.