"We were very close friends," Stephen James Porter, 51, said from the witness stand in the ACT Supreme Court.

"It felt like he was my little brother."

Porter's voice began to crack as he said this during a disputed facts hearing on Thursday.

The Macgregor man, who coached junior Australian rules teams at the Belconnen Magpies and the Ainslie Football Club, has pleaded guilty to four charges over child sex offences committed between 2009 and 2020.

He admits using one Canberra boy for the production of child exploitation material, having an "unlawful sexual relationship" with a second, and grooming a third. The other offence is one of possessing exploitation material.

The details of the most serious crime, which is the "unlawful sexual relationship", are currently being examined in order to sort out a factual disagreement.

Porter claims there were no more than 15 occasions on which he and the boy in question had sexual contact, while prosecutor Andrew Chatterton has told the court the correct figure is somewhere between 35 and 40.

When called by defence barrister Jack Pappas to give evidence on Thursday, Porter said he had "a genuine interest" in coaching boys to improve their football skills.

He said this was why he approached the parents of the victim of the "unlawful sexual relationship" with a private coaching proposal in 2014, denying he used his position at the Ainslie Football Club to gain access to the boy purely for sex.

But Porter admitted going on to have about three years worth of inappropriate sexual contact with the boy between 2015 and 2018.

While he conceded he had initiated this and acknowledged his awareness of the fact it was "morally wrong", Porter said he believed at the time the victim was a willing participant.

The court heard he had described the boy, in WhatsApp messages with a friend, as "one in a hundred million".

"I felt that [the victim] had the same sexuality as me, and I wanted to pursue that," Porter said.

The 51-year-old added that he had never forced the boy to have sex with him, saying he "left it up to [him]" in terms of what they did.

This issue was raised in relation to another dispute, which revolves around Porter's contention that a particular type of sexual activity only happened twice.

Under cross-examination, Porter denied Mr Chatterton's suggestion that this sort of activity was a much more regular occurrence and something that was "on the menu" throughout nearly the entire offending period.

He said it had only happened twice because the boy had made it apparent it was not enjoyable for him.

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Porter claimed he had similarly respected the boy's wishes by not continuing to make sexual advances after the victim "rebuffed" him twice around September 2018.

"I still cared for him," Porter told the court.

"I wanted to do the right thing."

Mr Chatterton put it to Porter that he was lying about the nature and frequency of his sexual contact with the boy, suggesting their relationship was "based on your needs, not his".

Porter disagreed with this proposition.

The issues in dispute must now be determined by Justice Chrissa Loukas-Karlsson, who will receive written submissions from Mr Chatterton and Mr Pappas in the coming weeks.

Porter, who remains on bail, is due to then face a sentence hearing in February.

The court heard on Thursday that he had coached on a volunteer basis, and had resigned from his ACT government IT job after his crimes came to light.

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