Natalie Hemming, 31, was last seen alive in Hemel Hempstead, Hertfordshire, on 1 May. She was found dead on 22 May.
Jurors at Luton Crown Court were shown CCTV of Paul Hemming, 43, with the children at Whipsnade Zoo.
Mr Hemming, of Milton Keynes, admits manslaughter but denied murder.
He wept in the dock as the video footage was shown.
During a police interview on 4 May, soon after Miss Hemming was reported missing, he told officers: "I deny all allegations of murdering Natalie Hemming or causing her harm."
In another interview shown to the court, he told detectives the dog had soiled a rug missing from the house.
When asked about 13 spots of blood on the coffee table he answered that it could have come from any member of the family.
The court was told Mr Hemming was overheard in the cells saying "I suppose I'm going to be charged with murder now", but then refused to acknowledge he had said this.
The court also heard a statement from John Goalby, who found Miss Hemming's body in woodland at Tom's Hill, Chandler's Cross on 22 May, while he was cutting the meadow using a quad bike towing a grass cutter.
He said he could smell rotting flesh and thought it could have been a deer.
When Mr Goalby found the body he saw dark hair, arms and fingers. The body was in a position where it looked like it had been dragged.
Mr Hemming has admitted obstructing a coroner in the execution of his duty and preventing the lawful and decent burial of a dead body.
The trial continues.
A man accused of murdering his partner took her children to the zoo the day after he is alleged to have killed her, a court heard.