If your partner already lives in New Zealand, or you and your partner wish to visit New Zealand together, then, you might be eligible for a partnership visa.
This partnership refers to the relationship between two people (similar or opposite sex) who want to live together for various purposes like a legal marriage or a civil union. For this, both the partners need to show enough evidence that they are living in a legitimate, honest, and a stable relationship prior to they receive a partnership visa. The evidence will be more credible when received from official sources. For example, an agreement describing the date that you and your partner started renting a property together.