It's a legitimate concern and it's good to think these things through before the move.
I moved to Australia for a contract in 2003 and met my (soon to be) husband. I had planned on staying 8 months; it ended up being almost 3 years because of him. He had migrated from the UK about a year earlier and LOVED Sydney/Australia. I never warmed to the place, though I've much fonder feelings now that I no longer have to live there. When I met him I was clear that Canada was home. We ended up coming to Vancouver a year earlier than planned because of an ill parent and my fundamental unhappiness.
After nearly 7 years, it's clear Vancouver and Canada are not quite right for him. He's been very gracious most of the time and hasn't pushed about anything. But I love him and I want us both to be happy. Long before I met him I loved NZ and planned to retire at least part/time there. So I've kept an eye on the career horizon and when a job opened up earlier this year I went for it. Without saying anything to him. Suffice to say he was surprised when I told him about my upcoming Skype interview. We were both surprised when an offer was made, which, after some negotiatiion, turned out to be a very, very good one.
We're not moving simply because he's not as happy as me: I am ready for a change and having the logistics of the move organized and paid for by someone else is FINE BY ME!!!! It does mean I'll be going to Auckland 6 months before he can join me though. That sucks.
But I've been to NZ many times and we've family and friends there already.