Bruce Willis' wife Emma Heming Willis is opening up about the "hard" moments of the actor's health battle.

The beloved actor's family revealed in 2022 that he had been diagnosed with aphasia, a language disorder that affects one's ability to communicate, and they shared his frontotemporal dementia (FTD) diagnosis the following year.

In a preview for the new sit-down interview Emma & Bruce Willis: The Unexpected Journey that airs on Tuesday (August 26) night, Emma got emotional as she spoke to Diane Sawyer about seeing "moments" of the Diehard star's personality amid his dementia diagnosis, per People.

"It's his laugh, right? He has such a hearty laugh," she said. "And sometimes you'll see that twinkle in his eye, or that smirk. I just get transported."

While seeing glimpses of her husband's "warm" personality may be heartwarming to witness, it's also a double-edged sword because of how fleeting they they can be.

"And it's just hard to see, because as quickly as those moments appear, then it goes," she said through tears.

Emma, who shares daughters Mabel, 13, and Evelyn, 11, with Bruce, recalled troubling signs she noticed prior to his diagnosis that hinted that something may not be right.

"For someone who was very talkative and very engaged, he was just a little more quiet... And when the family would get together, he would kind of just melt a little bit," she said, adding, "He felt a littler removed, very cold. Not like Bruce, who is very warm and affectionate. To go in the complete opposite of that was alarming and scary."

Despite this, she still feels "grateful that my husband is still very much here."

In addition to Mabel and Evelyn, Bruce is a dad to daughters Rumer, 37, Scout, 34, and Tallulah, 31, whom he shares with ex-wife Demi Moore. Since his health battle was shared publicly, they have continued to let fans in on special moments with their dad and shared candid insight into their family life.

Emma & Bruce Willis: The Unexpected Journey airs August 26 at 8 p.m. ET on ABC, and will be available to stream on Hulu and Disney+ the next day.