Depends on how strict the line is about mixed gender roommates. My line requires that a couple be 'registered' - i.e. married, or they have to fill out a form and show proof of living together outside of a ship situation.
However . . . as you're being hired as part of a group, the ship/entertainment division already has the cabins from the previous group. So - if you're part of a quartet - most likely there's 2 double cabins assigned already, though usually single gender.
Willing to bet you're being hired thru an agent? If you're not in contact with the shoreside/cruise line hiring person, ask them to put in the request that you room together.