When working onboard a cruise ship, you will most likely get very close to many people. However, when it comes to relationships, there are completely different challenges than on land.
Crew members may date other crew members, but fraternizing with passengers is prohibited. If your significant other or family are onboard your ship, as long as you get special permission from the higherups, you may be allowed to go into their passenger cabins, or even bring them into crew areas. Just make sure you know your allowances before doing something that could get you fired.