Defense lawyers portray Sinclair as the victim of an overzealous military under intense political pressure to make an example of him. They said in opening statements that the captain's journal entries never referenced fear, other than worrying that Sinclair loved his wife and would never leave her.
"I'm so in love with him," the defense told the jury her entries read. "I do know that I love him incredibly. ... I love him almost unconditionally."
The defense also said the woman sent Sinclair thousands of text messages, often sexually explicit. She sent messages even after he tried to break it off, according to the defense.
Prosecutors said that they plan to ask the captain to take the stand later Friday. The Associated Press generally does not identify those who say they were sexually assaulted.
On Thursday, Sinclair, 51, pleaded guilty to three lesser charges that could send him to prison for up to 15 years. That plea is sure to end the military career of a man once regarded as a rising star among the Army's small cadre of trusted battle commanders.
Sinclair now faces five other charges stemming from the claims of the female captain. She is nearly 20 years his junior and says the general twice forced her to perform oral sex.
By pleading guilty to the lesser charges, Sinclair's lawyers believe they will potentially limit some of the salacious evidence prosecutors can present. It will ultimately be up to the judge to determine what, if any, limitations to place on evidence as the case unfolds.
The former deputy commander of the 82nd Airborne could be sentenced to life in prison if convicted of the sexual assaults.
Judge Col. James Pohl accepted Sinclair's plea after nearly three hours of often intimate questions about the married general's flirtations and dalliances with four women — three military officers and one civilian.
The general pleaded guilty to having improper relationships with two female Army officers and to committing adultery with a third, the captain who was his longtime mistress. Adultery is a crime in the military.
He then described how the affair began during a war tour in Iraq when his primary accuser asked if he wanted to watch a movie. Once they were alone in his quarters, the general said the young officer made sexual advances that he initially rebuffed.
Pohl asked how Sinclair knew the woman wanted to have sex with him.
"Probably when she took her top off, sir," the general said with a nervous chuckle.
Sinclair's wife of nearly 30 years has remained with him through his legal troubles and served as a staunch public defender. The couple has two children.
The general also admitted to violating orders by possessing pornography and to conduct unbecoming of an officer and a gentleman. After he knew he was under investigation, Sinclair also admitted to deleting nude photos from a personal email account sent by a civilian woman with whom he was childhood friends.
In pleading guilty to possessing a cache of porn on his laptop in Afghanistan, a violation of orders for soldiers in the socially conservative Muslim country, Sinclair's defense hopes to limit the ability of prosecutors to use those graphic images to shock the jury. The jury is made up of five generals because in a court-martial an officer can only be judged by his superiors.