Barbara and George H.W. Bush shared a 'perfect' exchange before her death

"Pearls of Wisdom: Little Pieces of Advice (That Go a Long Way)" is a new book that collects some of the classic wit, sage advice and enduring stories from the life of former first lady Barbara Bush.

And one story in particular is sure to bring a tear to the eye of any reader who loves a good love story — because that's just what she and former President George H.W. Bush had, all the way to the end.

In other words, grab a tissue now!

"They were still playful and liked to poke fun at each other even in their 90s," Evan Sisley, a personal aide to the former commander in chief, recalled in the book that hit stores Tuesday. "Once when President Bush was doing a breathing treatment, he was waving the nebulizer device while periodically puffing on it from the corner of his mouth like it was a pipe. Mrs. Bush walked in and said, 'George, you really must shut your mouth,' encouraging him to properly seal his lips around the device and ingest the medication that was supposed to help him breathe. In standard Bush form, President Bush responded with, 'What's good for the goose is good for the gander.'"

That sassy exchange mirrored a much more significant one the couple had the day before Barbara's death in April 2018.

"President Bush wanted to let her know that he understood that she was dying and that it was going to be OK," Sisley explained. "He went into the living room and said, 'Bar, I'm not worried about you.' She looked up at him from her chair where she sat needlepointing and said, 'I'm not worried about you either, Georgie.'"

According to Sisley, although it wasn't a "grand statement," it was "perfect," adding, "They spent a life protecting and devoted to each other. They were secure in their faith, and they knew where the other was heading. They just wanted each other to know that it was going to be OK."

George and Barbara were married for 73 years, and he died less than eight months after his wife.

"They believed in life devoted to the service of others, and their devotion to each other was the finest example of that creed," Sisley continued. "Barbara Bush showed me, not by words, but by example how to be a spouse; how to be the fierce protector of another human being while also putting their needs before your own. Actions speak louder than words."

Sisley then ended the story with the words the devoted duo said to each other at the end of every night: They simply loved the other "more than tongue can tell."