Eric Roberts recently opened up about the most challenging time in his relationship with his daughter, Emma Roberts.

During his appearance on the 'Inside of You' podcast with host Michael Rosenbaum, published on Tuesday, October 22, he reflected on their relationship, calling it "indefinable."

When asked about the toughest period in his life, he said it was "probably the loss of relationship with my daughter," and acknowledged the sadness that comes from human misunderstandings that might never be resolved.

"Because we're human," he said.

His comments come on the heels of the actor's recent memoir, 'Runaway Train: Or, The Story of My Life So Far,' in which he talked about his public falling out with his sister, Julia Roberts.

In the book, Roberts also issued a "public apology" to Julia for past remarks he made during their beef. He admitted that his statement about her fame, "If it wasn't for me, there would be no Julia Roberts," was inappropriate and expressed his hope for reconciliation.

"It was an asinine thing to have said," he wrote.

In his memoir, the 68-year-old also discussed how his struggles with drug addiction affected his family. One of the biggest consequences, he shares, was losing custody of a young Emma. This led to a significant rift between him and Julia, who sided with Emma's mother, Kim Cunningham, during the custody battle. Reflecting on the situation, Roberts acknowledged that his sister made the right decision at the time.

Premiere Of New Line Cinema's "Valentine's Day" - Arrivals
LOS ANGELES, CA - FEBRUARY 08: Actresses Emma Roberts (L) and Julia Roberts arrive at the premiere of New Line Cinema's "Valentine's Day" held at Grauman's Chinese Theatre on February 8, 2010 in Los Angeles, California. Kevin Winter/Getty Images

Despite their complicated history, Roberts remains hopeful for the future, writing, "I imagine I will remain as Julia's brother and Emma Roberts' dad for the rest of my life. I'd like to make good on that."

He views his memoir as a step toward making peace with his past.

"Babylon" Global Premiere Screening - Arrivals
LOS ANGELES, CALIFORNIA - DECEMBER 15: Eric Roberts attends the Global Premiere Screening of "Babylon" at Academy Museum of Motion Pictures on December 15, 2022 in Los Angeles, California. Frazer Harrison/Getty Images

Earlier this year, Roberts appeared on the 'Still Here Hollywood' podcast where he reiterated that he is not allowed to talk about his sister or daughter publicly.

However, when asked which actors he admires, he expressed immense pride in Emma's work, saying, "I'm so proud of her I can't see straight."