Kenneth Haupai Mathew Smith bit a woman after becoming frustrated at being locked out of the house.
Smith pleaded guilty to contravening a protection order and common assault when he appeared in the Whanganui District Court on Tuesday.
"He had been drinking so she locked him out," Smith's lawyer RichardLeith told the court.
Smith and the victim shared responsibility for four children they had together, Mr Leith said.
"The situation was he had expected to be able to come there because he was looking after the children the next day. She locked him out because he had been drinking.