"It is a bit of a statement - you know that you are a part of it, a part of this person's journey," she told the Herald on Sunday.
"We have our children and even though we've had our ups and downs I was stoked. I was wearing a beautiful dress from a Tel Aviv designer and I was made up - it felt like it was my wedding day," she beamed.
Bennett's acting career has blossomed in recent years - including roles in all three Hobbit films, plus starring in international TV hit shows Arrow and Spartacus, but Karin has faced a nightmare few years. "I was 26 the first time I got cancer in my right breast ... [In January last year] I had about 10 tumours in my other breast. Because it was my second time I felt my body had betrayed me.
"I decided to have a double mastectomy and remove my ovaries at the same time. I am finishing the reconstruction next year."
Karin and Bennett have three daughters: Huia, 7, Mokoia, 4, and Pania, 3.
Karin says the love and support of her family and friends have kept her going while Bennett has been offshore filming.
Bennett, who plays Slade Wilson in the television series Arrow, told the Herald on Sunday he was enjoying spending time with his girls and acknowledged being away from them was tough.
"This has been a tough journey for me, Karin and our little family for the last couple of years," he said.