Brian Chapman, 55, is on trial at the Old Bailey for double-claiming for hotels and flights as well as pocketing refunds for cancelled flights between 2007 and 2011.
Mr Chapman, who commuted from Scotland to London, racked up £94,000 in credit card debts by 2011, the court heard. But his wife Margaret said that she was unconcerned about his gambling habit and unaware of the full extent of his debts.
The part-time supply teacher said she had never considered her husband to be dishonest, adding: "We have been married for 23 years. I know him very well."
On his gambling, she said: "I was quite happy. I did not think it was a problem. I thought it was under control."
Under cross-examination, Mrs Chapman said her husband had never told her there were any serious money troubles. When pressed, Mrs Chapman recalled one occasion when she had seen their mortgage repayments had bounced.
Mr Lodge went on: "You were aware of Brian's gambling or betting. What was the maximum he would bet? She said: "It varies."
Mr Chapman, of Cumbernauld, North Lanarkshire, denies fraud.
The trial was adjourned until Monday.