Yea, I think you should give her the opportunity to enjoy the cruise without ruining it at the end. Either let her go with someone else, or at least let her have some fun meeting other guys on the cruise. It's probably a good environment to get over someone.
"Oh Lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, cause I get better loking each day. To know me is to love me, I must be a hell of a man. Oh Lord it's hard to be humble, but I'm doing the best that I can." Mac Davis