"I've had a year to think of nothing but the charges that I am facing," Dunnett said.
"Are you sure you actually remember what happened or what you would like the court to remember?" Mr Thornton said.
Dunnett said he had not lied in his testimony because it would only "worsen" his situation.
Earlier in the day, the police officer conceded he twice touched a "playful and flirty" teenager's breast but was convinced it was "consensual" at a surf club party in 2011.
Mr Thornton questioned Dunnett's recollection of the events and said: "How can you remember more detail from one event and not another?
"I would suggest it's pretty memorable when you had 'the come on' from a 16-year-old girl and ended up in bed with her."
The Crown also questioned Dunnett's moral judgment for drinking with teenage girls at the surf club and claimed he should have known where the "mark' was.
"I would go out there to have fun," Dunnett said.
"And that includes having sexual intercourse with a 16-year-old does it?" Mr Thornton replied.
Dunnett said during one episode at the club, on Christmas Eve 2011, his "moral compass was broken due to intoxication".
Mr Thornton asked him if he "really believed a 16-year-old would want to be sexually intimate with a man old enough to be her father?"
"I'm sure somewhere in this world a 16-year-old is having a sexual relationship with a 37-year-old man," Dunnett replied. "Would I do it again, no. But what's the mark, where is the mark?"
"I suggest you consult your moral compass," Mr Thornton said.
The Crown also said Dunnett's evidence detailing the "extreme behaviour" of one of the complainants was "essentially unbelievable".
During his evidence, Dunnett said the complainant in a September 2011 incident at Ocean Beach was highly provocative and propositioned him several times.
He said the complainant had performed numerous grotesque and sexually suggestive positions in front of him, but he never indecently touched her despite Crown witnesses testifying to the contrary.
"It sounds unbelievable, I know. But it's true," Dunnett said.
Mr Thornton questioned why he had not asked a particular woman at the September party to testify in his defence.
"She's no longer my friend," the 37-year-old said.
When giving his evidence, Dunnett shook in the witness box and broke down in tears on a number of occasions.
Judge Les Atkins QC said he intended to reserve his decision on the verdict for two to three weeks after hearing final submissions from the Crown and defence at 11am today .
Yesterday, defence lawyer Jonathan Krebs submitted that one of the complainants, during her testimony as a Crown witness, did not give evidence regarding one of the counts of indecent assault in late 2011. Despite another witness giving evidence about the episode, Judge Atkins said the count would be discharged because there was "no evidence to support it".
Defence failed in an attempt to have another charge dismissed.
The trial will conclude today.