Even when people are living together (i.e. they have the same shared home because they are in an exclusive partnership), that doesn't mean they never spend any time away. (In the past, I had work that used to mean I spent periods of time in different places all over the country, but if someone said, 'Where do you live?' the undoubted answer would have been my home address.) So your partner making a family visit is not a bar to your application. But INZ will need an explanation for the reason for the trip (e.g. seeing family member who is in poor health, or sorting out personal property left with family), and also an account of how you keep in touch during your absence from one another (which can include phone records, print-outs of Skype conversations, etc., and possibly financial records showing purchases by either of you that will be for the benefit of both of you and your home). See here
https://www.immigration.govt.nz/new-...ly/partnership under
Time spent living apart.