Hello everyone!

I’m new to post forum but have read and liked it.
Now I want to ask questions about my boyfriend's and my visas.

Simple Question:
AFTER their relationship is once recognised by INZ, if someone has some separated period from his/her partner, will INZ give negative consideration in their next visa application process?

The details of my situation is following:
My boyfriend got accepted from a university in NZ and started his master’s study in February 2017.
Both of my boyfriend and I are from China(, meaning not having citizenship or residency of NZ or Australia.)
When he started his study, he got a student visa and it will expire soon.
I came to NZ with him with a partnership based visa and the expire date is the same as his visa.

During the first semester, he lost his interest in the subjects in his course and he found another course which was level 7 and taught online. He applied for the course and got accepted again. Then he applied for the variation of conditions and it was successful. After the variation of conditions is accepted, he dropped his first master’s course enrollment. Therefore his and my visa are still valid until now.

Soon after he started his second course, he went back to China to attend his cousin’s wedding and planed to see his parents and relatives. He could do that because his course was an online one and study in China. I chose to stay in NZ at that time.

The problem is here. He originally planed to stay in China for about a month or so and come back to NZ soon. But he stayed much longer than his original plan. He returned this year and we had separated for about a half year. The reason he stayed for such a long time was not something urgent like medical reasons. It was because he wants to spend time with his parents and was purely comfortable with his life in China.
Of course we have regular communications when he was in China. We talked online.

While he was in China, I could not go to see him because I was desperately looking for a job and I got a job offer in NZ and started to work in October 2017. I am still being employed by the same company.

Now his and my visas are running out.
Because my visa is running out, I need to renew my visa. I am about to apply for Essential Skills Work Visa and my boyfriend is planning to apply for a visa based on partnership with me this time. He cannot expand his student visa or apply for new student visa unfortunately. Because his course is taught online, they do not offer a new student visa although they considered the variation of conditions.

Now I am a little worried about our separation time. We have not been married in China. The recognition as partners on the visa in NZ is the only official recognition by official authority.

Here’s more personalised questions:
Is it possible that INZ denies our relationship stability and does not offer him and me visas? Or will they recognise our relationship automatically?
Is it possible that INZ still requires evidences of one year living together in the "last" one year, which we did not have this time?
Will INZ find out our separation by checking his entrance and departure records or other things that other NZ authorities have?
Although there is nothing illegal and people have free rights to travel, is it a problem for INZ that a student visa holder spend such a long time outside NZ?
Will INZ think we abused the visa system?
Will we be in any other troubles?

Thank you for reading and I appreciate any advisces and comments.