The death of his daughter a week ago followed that of her boyfriend a month ago.
The pair had briefly been "an item", and are understood to have attended the same school and youth group as another student who died.
Before her death, she had been active in her youth group, enjoyed playing sports and was popular.
"It's so surreal to me at the moment. There was no indication that she was going to do it. There was no depression. I can't understand it."
She had a loving family and a network of friends.
He urged parents to spend time with their children and to treasure it: "spend more time with your kids because they spell time as L.O.V.E."
Northland coroner Brandt Shortland says he will investigate the deaths of "a number of local teenagers" in Whangarei in the last few weeks to try to understand and learn from the tragedies.