Squadron leader Nicholas Tucker, 46, told Norwich Crown Court that he found 21-year-old Dijana Dudokovic "very flirtatious, fascinating to be with, very vivacious and a good interpreter". But he admitted the sexual side of their relationship had been a "bit of a disaster".
Sqn Ldr Tucker admitted that he had a brief affair with Ms Dudokovic, but denied murdering his 52-year-old wife, Carol.
He told the jury how he had taken Ms Dudokovic, 21, whom he had met while on UN peacekeeping duties in Bosnia, to the south coast and the New Forest when she visited England in June 1995. But the two occasions on which they had tried to make love ended in failure and frustration.
Sqn Ldr Tucker added: "To put it bluntly I couldn't hack it. After that, it was the time of the month for her. She had a period. I did not have sexual intercourse with her on any other occasion."
The prosecution alleges that Sqn Ldr Tucker, of Honington, Suffolk, murdered his wife by staging an accident at the river Lark near their home on 21 July 1995.
It is claimed that he had become infatuated with Ms Dudokovic.
Sqn Ldr Tucker described to the court events leading up to the fatal incident. He and his wife had gone out for dinner to the Red Lion pub in Icklingham and were on their way home when he missed a turning. "We were chatting, Carol shouted something to me to the effect `mind the deer', she saw them before me momentarily. I would say I was doing more than 30mph. My recollections are she grabbed the steering wheel. I say that because the movement to the left was more than me steering. At that point I saw two animals on the road, my immediate thoughts were they were dogs, perhaps about the size of a labrador."
Sqn Ldr Tucker said he has "three pictures in his memory" for what happened next. Firstly, he recalls, the animals and then "a reflection with the headlights shining off some weeds. And the last one is water cascading down the window. "The next thing I can remember is some white lights and someone talking to me. I think it was in the ambulance."
After the crash Squadron Leader Tucker said he suffered bruises, aches and pains and discovered he had grazed his forehead. He said: "My concern was obviously to know how Carol had died."
The case continues.