Mike, I don't know how one can go through an entire cruise and only spend $7. Like Dave said, that's one drink o the day special!
Well, that does exclude excursions and tips. But otherwise you are right - she bought one drink of the day! Yes, she is frugal, but she has a different mind set than most - she feels that she is getting so much great stuff for the price she already paid, that she doesn't see the need to spend more. As a young couple that has big expenses coming up, she sees it as not necessary - she gets enough enjoyment out of what she already has. And when it comes to drinks, it's also about the calories haha - drinking a few hundred calories in one glass isn't too appealing to her while eating three large, unhealthy meals a day.