"What the argument was about is, you saw that she had a Facebook message that was from a male friend. Your anger about that is a concern.
"It shows a controlling nature by you. She's an adult. She's entitled to have male friends. You don't control her, but you tried to.
"You tried to control her by using violence against her. You punched her not once, but twice in the head with a closed fist, striking her in the right eye and right side of her jaw."
Winiata's partner was admitted to hospital where she had her eye examined.
Judge Morris said she saw photographs of the injuries that Winiata caused her.
"Sometimes with punctures as severe as that, close range, by someone such as you, causes the cornea to detach.
"People can go blind in their eye."
Winiata has previously had domestic callouts said his lawyer, Richard Leith, but has no previous convictions related to domestic violence.
Judge Morris sentenced Winiata to 200 hours' community work and 12 months' supervision.
"Now's the time Mr Winiata, you are still young at 25, to commit to ensuring that you don't get yourself in that position of standing in the dock again for domestic violence.
"If you do, I'm afraid that imprisonment will be the only sentence that is possible and I put a final warning in respect to domestic violence on your record."
Winiata was also convicted and discharged for failing to answer district court bail.
