JandM is right that you've found your own answer
I currently have a partnership sponsored work visa (1 year validity) through my boyfriend.
Me and my boyfriend (NZ citizen) were in pretty much the same situation you and your partner are currently in ie
never lived together.
I too was from a country where working holiday visas are difficult to obtain and in fact tried but failed to obtain one.
We met online and were in a long distance relationship, only meeting and staying together during vacations which INZ does not classify as "living together"
Here is the timeline of what we did
May 2016 - I arrived in NZ on 3 months visitors visa
July 2016 - Apply for 3 months extension on visitors visa (making sure I am in the country legally to allow sufficient time processing of work visa)
Aug 2016 - Acquire 3 months living together, submit evidences to Immigration NZ
I heard back from INZ within 3 weeks and am thankful and happy to say I currently have a partnership-sponsored work visa.
Hope it helps!