Diane Keaton’s health took a turn in her final months that even shocked her loved ones.

Actress Diane Keaton died in California at age 79. (Credit: Jerod Harris/Getty Images)

“She declined very suddenly, which was heartbreaking for everyone who loved her,” a friend of the actress who died on Oct. 11 at age 79 told PEOPLE. “It was so unexpected, especially for someone with such strength and spirit.”

“In her final months, she was surrounded only by her closest family, who chose to keep things very private. Even longtime friends weren’t fully aware of what was happening,” the source added per the outlet.

Another big change that took her friends and family by surprise was that Keaton put her “dream home” up for sale in March of this year. According to the beloved actress and serial house flipper, her Los Angeles home was her forever home, and she planned to stay there permanently. The “Book Club” star even wrote a design guide called “The House That Pinterest Built,” detailing her gut renovations of the Sullivan Canyon estate to help increase its value from the initial $4.7 million sale.

A friend of Diane Keaton’s says the actress’ health “declined very suddenly” before her death. (Credit: Matt Winkelmeyer/Getty Images for CinemaCon)

Earlier this year, the Oscar winner listed her five-bedroom, seven-bathroom mansion for nearly $29 million, according to Realtor. The L.A. native told Architectural Digest in 2017 how much she loved her remodeled 1970s home.

“I’m still in love with it; I’m still in love with Pinterest!” Keaton said. “To me, it’s soothing, because you’re also on a hunt. It leads to something else, and that leads to something else, and it just goes on and on. And that’s the light you want — the light from the computer. It just makes everything look better.”

(L-R) Duke Keaton, Diane Keaton, and Dexter Keaton (Credit: Emma McIntyre/Getty Images for Turner)

Although the “Father of the Bride” star never married, she is survived by her two kids, Dexter and Duke, who she adopted in her 50s. Keaton has received an outpouring of love from her friends and famous co-stars remembering the Hollywood legend following the shocking news of her death.