One theory was that Captain Zaharie's marriage to his wife Faizah had ended, that he was having problems with a new girlfriend and was mentally unstable. However, his family have rubbished that claim.
Asuad Khan, brother of the pilot's wife, said the rumours were false.
"I can see that a lot of people are saying a lot of things about him which is untrue," he told ABC Australia's Four Corners programme. Speaking on behalf of his sister, he confirmed she had not left Captain Zaharie.
He did not know whether his brother-in-law had a girlfriend, but said it would not have been a problem.
Mr Khan said Captain Zaharie "had a good life". "He had a lot of money, and he loved his daughter very much," he said.