She sunk her teeth into her the victim's back and held her grip for 10 seconds, Judge Michael Turner said.
With tempers at boiling point, Fleming then turned off the power at the mains to stop him using the phone.
When power was finally restored, police were called.
Fleming was arrested but offered no explanation for her attack.
Defence counsel Deborah Henderson told the court yesterday her client still could not rationalise her actions.
"It is clear she's extremely remorseful and ashamed of this behaviour," she said.
Her former partner suffered a visible bite mark on his back but in his statement to the court, he refused to retaliate and said the chomp did not cause him much discomfort.
He wrote that he did not want the police involvement and had objected to the matter going to court.
The victim wanted the relationship to continue, but Fleming confirmed yesterday that the pair had split.
Despite the biting incident, the man believed the defendant was a caring person and cited a time earlier in their relationship when she helped him recover after back surgery.
The fact she knew that area of his body was sensitive and still targeted it was an aggravating factor, Judge Turner said.
Fleming's criminal record also did her no favours.
The judge noted more than six previous breaches of sentence and another domestic-violence assault from 2011.
She was convicted of assault with intent to injure and breaching a previous community-work sentence.
Judge Turner imposed three and a half months' community detention with a weekend curfew. He also sentenced Fleming to six months' supervision to address her "underlying issues".
