I just keep thinking, the longer they operate under the assumption it's okay, the more
damage there will be to the friendship. While M's been thinking "No way" for months, they'll be shocked and surprised--especially if it's short notice. Besides, a trip like this is a major undertaking--booking airfare, the cruise, dealing with work, etc. If there's a looming "No," I'd want learn about it sooner, rather than later. The impact may be big enough to scrap the entire trip. And again, I'd rather know now...before having to pay cancellation fees , etc.