My boyfriend got a green card in New Zealand. Can he vouch for me?

You must prove a stable relationship. .

So you need proof of cohabitation, proof of common fixed assets, common account, photos and so on.

Even if he is married, he is not qualified to directly guarantee because there are too many fake marriages.

But if you get married, you can get a tourist visa.

If you don't decide and don't have these materials, I suggest it's easier for you to sign the tour yourself, otherwise there will be too many materials provided and it will be more troublesome to review. When you come over, change your study visa or something, and you can do PR after living together for one year.