Businessman Shrien Dewani confessed he needed to "find a way out of" his marriage months before ordering his wife's murder, a court has heard.
The wealthy care home owner is wanted in South Africa over accusations he arranged a hit on his bride Anni on honeymoon in November.
An unnamed witness is prepared to give evidence that he had revealed his reluctance to marry her more than six months earlier, his extradition hearing was told.
This came as an expert witness on South Africa's prison system warned that claims Dewani was gay put him at risk of sexual violence if he was jailed in the country.
Hugo Keith QC, representing the South African authorities seeking the extradition, said: "Dewani told (the witness) in April 2010 how he was engaged and had to get married.
"He said although she was a nice, lovely girl who he liked, he could not break out of the engagement because he would be disowned by his family. He went on to say to the witness he needed to find a way out of it."
Meanwhile Sasha Gear, from Johannesburg's Centre for the Study of Violence and Reconciliation, told Belmarsh Magistrates' Court on the first day of the extradition hearing that Dewani's youthful good looks and alleged homosexuality would put him at risk if was jailed in South Africa.
"What I know about Shrien Dewani is he's likely to be very vulnerable to sexual violence because of certain of his characteristics," she said.
Among these were the fact that he is not an experienced criminal with "street credentials"; his unfamiliarity with the place he is likely to be incarcerated in and the local slang; the publicity surrounding his case; and the fact that his alleged crime was not violence against another man and so would be less "worthy of respect", she said.
Mrs Dewani, 28, was shot dead in the back of a taxi in Cape Town after her husband allegedly arranged a hijacking.