Correction: An earlier version of this article incorrectly said that the McDonnells’ 2011 family vacation to a state-owned cottage took place at Camp Pendleton in Southern California. The Camp Pendleton where the McDonnells vacationed is in Virginia Beach. This version has been corrected.

The defense rested in the federal corruption trial of former Virginia governor Robert F. McDonnell and his wife, Maureen, on Wednesday with a final and especially poignant look at the couple’s marital troubles, strife that has formed a core of their joint defense.

It came from the couple’s oldest daughter, Jeanine McDonnell Zubowsky, and it was a sign of the sensitivity of her testimony that she opened by asserting, in turn, that she loves her mother and her father “very much.”

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But throughout the nearly five-week trial, the McDonnells have insisted that it is necessary for them to lay bare the crumbling state of their 38-year marriage to fend off charges that they worked together to sell the influence of the governor’s office to a dietary supplement executive in exchange for $177,000 in loans and luxury gifts.

Their attorneys have argued that the couple could not have conspired because they were barely speaking when they occupied the governor’s mansion. Maureen McDonnell developed an emotional attachment to the businessman, Jonnie R. Williams Sr., in place of her husband, they have said.

Zubowsky, an Army veteran, testified that her father was consumed by the demands of his career and sometimes neglected his wife as she raised their children. Maureen McDonnell felt “frustration, loneliness, anger, at times,” her daughter said, and turned to soap operas, drinks and long baths to relieve stress.

“It was frustrating, and she felt alone at times,” Zubowksy said. “I think she was depressed, so she would try to escape.”

Zubowsky, 33, was one of four witnesses who testified for the former first lady Wednesday. By day’s end, the defense had handed the case back to the prosecution. Prosecutors indicated that they have one more rebuttal witness to put forward Thursday as the trial moves quickly toward a conclusion.

Lawyers are expected to deliver their closing arguments Friday, and then the seven men and five women of the jury will deliberate on a verdict.

Zubowsky said her mother worked as a waitress and a typist to help put her father through law school. As Robert McDonnell’s career took off when he became a prosecutor and a state delegate, Zubowsky said, her mother grew increasingly isolated at home with their five children, including twin sons born in the early 1990s.

When he became attorney general and then governor, she said her parents found their “fantasy” abutting “reality.”

“I think it was a lot harder when they were actually living it,” she said.

Though her father coached his children to live within their means, Zubowsky said, Maureen McDonnell went on secret shopping trips and hid her purchases from her husband. When the bills came, and Robert McDonnell became aware of his wife’s extravagancy, arguments ensued.

Zubowsky said her father confided to her once about his marriage, while on a family vacation to a state-owned cottage at Camp Pendleton in Virginia Beach in July 2011.

“I don’t know what to do anymore,” she said her father told her. “I can’t make her happy.”

Zubowsky said she watched them put on a facade in public as a happy couple but said that was no more than an “act.”

“Any time they went into a public setting, it was like a switch flipped,” she said.

She testified that when Williams came into the family’s lives — along with his product, Anatabloc — her mother displayed an unusual interest in the businessman.

“I think she had a mild obsession with Jonnie,” Zubowsky testified. “I had never heard her talk about any other friend in this manner.”

Williams was generous to Zubowsky and her husband, Adam, as well, she testified, giving the couple a $10,000 check in lieu of a generator as a gift for a tool party, a male version of a bridal shower, in late 2012. The two were married in May 2013 and are expecting the McDonnells’ first grandchild in January.

Zubowsky said that she was “overwhelmed” by the size of the gift, but that she put it in perspective because she knew of Williams’s wealth. She acknowledged that she never told her father about the gift, saying it made her “uncomfortable.”

“That is not the way I had ever operated before,” she said.

After news of the investigation of the McDonnells’ relationship with Williams became public, Zubowsky said she and her husband returned the money.

Or, as she put it on the witness stand in an answer that drew an immediate objection from prosecutors, they returned the cash, “once we realized that Jonnie himself was a criminal.”

A friend of Maureen McDonnell testified to reinforce the image of the former first lady as an anxious, overly trusting woman who was overwhelmed by life in the governor’s mansion and shared a common passion for dietary supplements with Williams.

April Niamtu described Maureen McDonnell as a “very trusting” and “very gullible” person, who chewed her fingernails out of stress. She appeared to be “best buddies” with Williams.

The former first lady’s attorneys contend that Maureen McDonnell helped Williams not to get his money but because of her genuine belief in their friendship and Anatabloc.

From start to finish, the trial has taken jurors on an emotional ride, and Wednesday was no exception. After Niamtu’s and Zubowsky’s intensely personal testimony, prosecutors called two witnesses with far more fleeting connections to the case, and they offered a sort of comic relief to an otherwise somber day.

The first was party planner James Abel, a friend of Maureen McDonnell’s chief of staff who had a chance encounter with Williams at an April 2011 event in New York City.

Abel said the first lady’s chief of staff, Mary-Shea Sutherland, introduced him to the businessman at the event, and the two of them got to talking after Sutherland left to work. At one point, Abel said, Williams pulled out some Anatabloc in what looked like a “modern, cool, hip tic tac container” and talked of how he would soon be launching the supplement on the market.

Abel said he pitched Williams on having a launch party (important, because defense attorneys have suggested Sutherland was the brainchild of that idea) and even suggested creating 20-foot-tall Anatabloc bottle replicas for guests to walk through.

Williams eventually had lunch at the governor’s mansion on the day Anatabloc went to market, but Abel said he wasn’t involved in planning it. Williams, he said, did not respond to a follow up e-mail, and the one time he got the businessman on the phone, he was only interested in acquiring “vintage bricks” for a three-quarters of a mile driveway.

“My response was, ‘I’m a party planner,’ ” Abel said, drawing a laugh from the courtroom.

Prosecutors also called to the stand Matthew Hunter, a former employee of Williams who drove the businessman’s now infamous Ferrari to his Smith Mountain Lake house for the governor to use while on vacation.

Hunter’s testimony was important because he disputed McDonnell’s vague recollection that he might have first noticed the Ferrari in the garage; Hunter said he left the car in the driveway. But it was interesting in another respect.

Hunter said he picked up the car to take it to the lake house from a Richmond-area Cracker Barrel restaurant. Williams — the man who sprung for luxury vacations and admitted pouring out $5,000 cognac just to see what would happen — was dining there with his family.

Carol Morello and Luz Lazo contributed to this report.