Cape Town - Guatemalan, Diego Novella told the Western Cape High Court on Tuesday of a tumultuous relationship with Gabriela Kabrins Alban, the woman he is accused of murdering.
Infidelity and two instances of assault within the relationship were brought up during cross-examination.
Prosecutor Mornay Julius read extracts from notes compiled by forensic psychologist Tania Swart.
"Mr Novella reports that they argued a lot," read Julius.
"He admits to eventually being unfaithful to her in Guatemala and, on discovering this, she physically attacked him."
Novella told the court that he and Alban had previously agreed to experiment sexually with a third party.
However, he said that Alban was not "consistent" with the agreement.
The accused also wished to clear up any rumours that he had been unfaithful with the domestic worker employed to take care of Alban, who was suffering from Lyme disease.
"She was fired because she was stealing," said Novella.
"Gaby was tired of her because she wanted things done a certain way and she didn't meet Gaby's requirements," he claimed.
The Guatemalan told the court that Alban was "difficult" as a result of her illness.
"She was very critical of me. Gaby was not an easy person to please," he said.
"I think all of this was fuelled by her taking the wrong medication and the business situation with her business partner.
"She felt very frustrated and it bothered her a lot that she couldn't function."
Since Alban moved in with Novella in 2014, he was "overwhelmed" by her "high demands" and "bad moods".
He told the court that he had even contacted her mother for assistance, to no avail.
Novella is accused of murdering the US sales executive at an upmarket hotel in Camps Bay on July 29, 2015.
The trial continues.