Imagine growing older in the company of the ever-so-hip and handsome Ethan Hawke and the luminous Julie Delpy.

Ardent fans watched their characters fall in love in Vienna in their 20s in the 1995 romantic drama, "Before Sunrise," and reunite with passion tinged with regret in their 30s in "Before Sunset" (2004). Now, as the characters near middle age, fans witness them wrestle with the cold realities of happily ever after in "Before Midnight."

Ethan Hawke and Julie Delpy in "Before Midnight" (2013) (Courtesy Sony Pictures Entertainment)

These movies have become underground classics, attracting legions of fans in part because they feel authentic.

In an interview with "Nightline," Hawke and Delpy described what it has been like for them to experience the journey of two star-crossed lovers over the course of the trilogy.

"We tried to get to a place with Celine and Jesse in those three films … to bring as much truth as possible," Delpy said. "It's really just trying to find the right balance of something that rang true. But, at the same time, it's totally fictional."

The two were first cast in "Before Sunrise" when they were in their 20s.

"When Julie and I watch the first film, "Before Sunrise," yeah, we're young," Hawke said. "Neither one of us have a wrinkle in the world. But we watch it and I remember how insecure we felt being that age."

Ethan Hawke and Julie Delpy in "Before Sunrise" (1995). (Courtesy Sony Pictures Entertainment)

Ethan Hawke and Julie Delpy in "Before Sunset" (2004). (Courtesy Sony Pictures Entertainment)

Both are now in their 40s, as are Celine and Jesse in "Before Midnight," and their lives on-screen and off have deepened.

"Julie and I both feel pretty passionately about this," Hawke said. "When you start telling young people that being 22 is the best years of your life, it's really depressing because you're completely discounting the idea of wisdom, the idea of growth, the idea of maturity, of knowledge."

"And being happy in your 40s," added the French actress, Delpy. "Because the truth is, when people ask me, it's like, 'Oh, you look back at the films,' and you are like, I was like, 'Oh my God, I was so miserable in my 20s.'"

"Before Midnight" opens in theaters nationwide on May 24.