I understand you spent the money on the cruise, and lord,I hate losing money too, and I know you were expected to bring someone. But the problem is , when you invite someone to something like that who is committed to you and was kind of flaky from the getgo, you run a high risk of loss. I for one, don't think you should be shaping your life and relationships right now around this cruise.
basically, I completely echo what J said in his last paragraph.