They are right, basically. They are interpreting 'living together' absolutely strictly, as in 'having their permanent base in the same home, right now', whereas some couples have actually got visas when they HAD done that for a while and had PLENTY of proof, but one partner, for a solid and provable reason (such as a new job to start, or their visa running out) had had to go ahead to NZ, so they were currently keeping in touch by email and Skype etc.. And/But this company are telling you the same thing I did in the post just above.
You should not be confused. The NZ immigration laws base the concessions for partners on evidence of living together, so that is what you have to arrange your lives to give them.