An ADFA cadet repeatedly attempted to have sex with a woman despite her protests and groped the woman several times in a separate incident, the ACT Supreme Court has heard.

Sebastian Crago Ellis has been charged with six sexual offences against the woman, most of which are alleged to have happened on a separate night about one month after the alleged groping.

Charges against Ellis include one count of rape, two of attempted rape and three acts of indecency without consent.

The alleged victim told the ACT Supreme Court she had an intimate relationship with Mr Ellis in 2016 after they met through a mutual friend.

The pair had discussed their sexual preferences in Facebook messages, where the alleged victim made her boundaries clear as their relationship developed.

The most serious offences allegedly occurred after the pair met up at a nightclub in July 2016, and the woman suggested the pair go to her room at the Australian National University, where she knew she could get latex-free condoms.

The woman maintains that when Mr Ellis suggested his room at ADFA instead, she told him twice there would be no sex because she had an allergy to latex.

She did consent to some sexual acts but said when Mr Ellis attempted to have sex with her she objected.

She told police she said to him: "You are not listening, you're not respecting my boundaries."

Ellis 'respected refusal', defence lawyer says

But Mr Ellis's lawyer Stuart Littlemore told the court there was a real dispute as to what happened.

"Every sexual act was by the consent of both the parties," he said.

"He respected her refusal."

He also told the court his client had considered the woman's boundaries saying the alleged attempts to have sex were "an unspoken question".

Mr Littlemore said when the woman said no, Mr Ellis stopped.

Mr Littlemore asked the jury to consider the size of Mr Ellis compared to the alleged victim, saying if he had wanted to have sex with her it would have happened.

"It's not physically possible for her to resist," he said.

A key part of the evidence is expected to be Facebook messages between the pair and a recording of a conversation between the two after the alleged incident.

Outlining the case on Monday, prosecutor Rebecca Christensen said the first incident allegedly happened in a nightclub when the woman claims Mr Ellis continued to grope her after she asked him to stop, and it only came to an end when she bit his lip.

Ms Christensen told the court that in a Facebook message later Mr Ellis apologised saying he could not remember what he had done.