The theory was presented to a Wake County jury in the murder trial of 63-year-old Leslie "Lester" Smith Tuesday.
Smith is accused of shooting 48-year-old Jaquelyn Larue Gore in his Wake Forest home July 26, 2009.
The shooting made headlines last year because of the 911 call Smith made right afterwards. In it, he matter-of-factly told the operator he has shot Gore point blank in the chest and refused to cooperate with any attempt to perform CPR.
"I don't wanna help her," says Smith in the call.
"You don't want to help her?" asks the operator.
"She's dead," he responds.
"She's dead?" the dispatcher asks.
"Sure looks like it," Smith responds.
Gore - called Jackie by her family and friends - was the daughter of Jackie Gore of the beach band The Embers.
In his opening statement Tuesday, District Attorney Colon Willoughby told jurors the couple had a tumultuous past.
"Ladies and gentlemen this is another story of domestic violence. This is about two people who can't live together and can't seem to stay apart," he said.
Smith's attorney, Karl Knudsen, doesn't deny Smith shot Gore, but he told the jury Tuesday that she led a troubled life marked by heavy drinking and violence, depression, suicidal episodes and promiscuity.
Knudsen also told jurors that his client had tried to get Gore to move out of his home, had just been laid off from his job of 20 years, had life-threatening medical issues and was awaiting a possible diagnosis of cancer.
He said Gore taunted Smith in the minutes before she was shot.
The jury was then presented with two defense theories about Smith's actions. Knudsen said Smith was either "provoked by the extreme verbal and emotional insults inflicted by a mentally ill and drunken abuser. Or, was it suicide by boyfriend?"
Later, with the jury out of the courtroom, the DA expressed his feeling about the defense's tactics.
"What I think this is is just a gratuitous attempt to trash the victim," offered Willoughby.
Willoughby called about a third of his 23 witnesses Tuesday, but the trial is not expected to go quickly.
The defense witness list is twice as long.