It is very important to be upfront and honest. It is possible that on a cruise under the starlight with the waves crashing on the ship and the clean ocean air clear for miles and miles that two strangers may fall in love and if that occurred they likely would kiss and hold each other.
It would be very nice if in addition to finding a cruise mate a man and woman found love and their spouse. But chances are that the cruise date is going to be just friends for a week, maybe just friends for one week each year, maybe friends that over time become more. Some of these cruise dates may not be dates at all but business trips or platonic friendships. Some of the men may even be gay men who want their family, friends, boss, or coworkers to think they are straight. A man is not being realistic if he expects sex from a stranger. The fact that he is paying for the date does not entitle him to sex. If a woman does not love a man he is not going to get sex and it is unlikely that the two would fall in love in one week.
Remember the couple will be sharing a room not a bed