The 34-year-old former rugby league international appealed against a NSW District Court decision that ordered him to pay his ex-wife almost $500,000 in December 2021.
Kirra Wilden sued her former husband in February 2020, alleging multiple instances of rape during their relationship in 2014 and 2015.
The damages awarded included $100,000 for her projected future economic loss due to the post-traumatic stress disorder she suffered from the alleged assaults.
The civil case did not require the alleged assaults to be proven beyond a reasonable doubt as a criminal trial would.
Jennings' appeal against the decision, arguing the future damages were excessive and alleging the onus of proof had been reversed during the civil trial, has been dismissed by the NSW Court of Appeal.
Acting Justice John Basten said Ms Wilden was not given undue favour, but her evidence was considered more reliable by Judge David Wilson.
"(She) was a careful and reliable historian who gave evidence with clarity," Justice Basten wrote in his judgment published on Tuesday.
"There was no reversal of the onus of proof, but a careful assessment of the plaintiff's evidence against a range of tests," he wrote.
In contrast, Judge Wilson found Jennings' evidence raised "concerns regarding his honesty generally".
He was also an unimpressive witness, reluctant to accept propositions put to him in court until they were demonstrated to be correct, Judge Wilson said.
The amount awarded for future economic loss was also not excessive, despite Ms Wilden currently being able to work, because a finding of post-traumatic stress disorder increased the risk she would earn less or be unable to work in the future.
"The PTSD developed as a result of the assaults," Justice Basten wrote.
Jennings denied the assault allegations and has not been criminally charged.
His 13-year NRL career effectively ended in 2021, when he accepted a three-year ban for doping.
However, Jennings has indicated he wants to return to playing when the ban expires at the end of the current season.
He failed a drug test and was suspended on the day of a 2020 elimination final, which his former Parramatta Eels team lost.
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