Ricky Jackson Winiata and his partner had been together for close to 15 months when an argument erupted between them that resulted in him assaulting her.
They were travelling in a car together at night when Winiata saw she had received a Facebook message and he immediately became enraged.
Winiata appeared in Whanganui District Court on Tuesday where he was sentenced by Judge Barbara Morris having pleaded guilty to a charge of male assaults female.
Judge Morris said Winiata had a controlling nature.
She's an adult. She's entitled to have male friends. You don't control her, but you tried to.
"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.