"It is, of course it is," Ryan said of he and his actress daughter's recent efforts to repair their relationship after a highly publicized, and highly dramatic, estrangement.
"It's a work in progress," Tatum, 47, added on "GMA." "Relationships are tricky."
A relationship so tricky that the Hollywood father-daughter duo found their best hope for reconciliation not in private, but under the bright lights of reality television.
The result is "Ryan and Tatum: The O'Neals," a "docu-series" debuting this Sunday, June 19, on The Oprah Winfrey Network (OWN).
"Let's have the conversation in a work setting and we'll find our way back that way," Tatum told "GMA" of their decision to open their lives once again.
"It was a way back when there weren't many paths," Ryan said of the show as a way to repair the father-daughter bond strained more than two decades ago after the "Love Story" actor left Tatum's mother, actress Joanne Moore, and began a stormy love affair with actress Farrah Fawcett in the mid-1970s, when Tatum was 15.
The documentary takes on those old wounds in the first episode, with Tatum saying, "He went to go live with Farrah, and I was just a kid. When I was 19, I ended up moving to New York. I was done being my dad's daughter."
In one emotional scene, Ryan, best known for his Oscar-nominated role in the 1970 tearjerker "Love Story," tells his side of moving out of the house where he lived with his daughter to move in with Fawcett.
"[Tatum] felt I had abandoned her and gone on off with Farrah which is somewhat true," O'Neal is shown saying in the OWN documentary. "I was so in love with Farrah that I was blind, and so yeah, she got left at the curb but I always said just stay at the curb, I'll be back."
"I thought I had all the pride," Ryan told "GMA" of what went wrong in his relationship with his daughter. "That broke our communication. We didn't have it so we drifted away from each other, unhappily of course."
In an interview on "LIVE! with Regis and Kelly" set to air Friday, for the first time, Ryan says he was in denial about his relationship with his daughter.
"It got a little bit raw at times and things that had been left unsaid -- but not for long, just twenty odd years -- suddenly were being said, and I was in denial, lots of denial," Ryan revealed.
'To Hell and Back'
So began a 25-year estrangement that left the father and daughter with only sporadic communication between them as they each endured their own hardships.
"If you're apart, you're apart," said Tatum. "He has his reasons and I have my reasons."
During their time apart, Tatum fell into a spiral of drug addiction that left her in-and-out of treatment and which caused her to lose custody of her three children with ex-husband John McEnroe.
In June 2008 she was arrested for illegally trying to buy crack cocaine off the streets near her Manhattan apartment. She pleaded guilty to disorderly conduct in connection with the arrest and agreed to attend a drug-treatment program.
"I feel like I've come from hell and back," Tatum said on "GMA." "Now I'm just trying to live with as much love in my life as possible.
Ryan, in the years apart, continued an on-again, off-again relationship with Fawcett, with whom he has a son, Redmond, and faced his own troubles with substance abuse, illness and violence.
In 1983 the actor allegedly knocked out several of his son, and Tatum's brother, Griffin's teeth and, in 2007, he made headlines again when he fired a shot at Griffin, whose pregnant wife was hit in the head with a fireplace poker during the melee.
In 2001 he was treated for, and recovered from, chronic myelogenous leukemia.
While apart, neither was shy about discussing past grievances and their tumultuous past.
Tatum penned a detailed memoir, "A Paper Life," in 2004 that became a New York Times bestseller, followed by, "Found: A Daughter's Journey Home," her new book released this week as the OWN show debuts, that recounts her attempt to repair her fractured relationship with her dad.
Their estrangement was so severe that Ryan did not even recognize his daughter when she attended the funeral of Fawcett, who passed away in 2009 after a long battle with cancer.
Tatum claimed that her dad hit on her at his lover's funeral, telling radio host Howard Stern, in an interview this week while promoting the show, that Ryan, "just saw this blonde hair and was like 'Hey baby!' and I was like, "Dad -- it's me!'"
Tatum noted to Stern that Ryan later bragged about the incident to Vanity Fair, adding, "He doesn't even know the difference of what makes him look bad."
'We Have a History'
Yet it was Fawcett's death that opened Tatum to the possibility of reaching out to Ryan again.
"That was the last thing to help to soften my resolve and help make a relationship work and help build the bond back," Tatum told "GMA." "And that was before the show was even a possibility."
Father and daughter knew, they both told "GMA," they had to take advantage of the only thing they shared, show business, to try to heal old wounds.
"This [the OWN show] looked promising because we work well together," Ryan said. "We have a history and I thought maybe we could make more history."
Ryan and Tatum's early history seemed, from the outside, like a Hollywood fairy-tale.
The two co-starred together in the 1973 movie "Paper Moon," for which Tatum won the Best Supporting Actress Oscar at age 10, the youngest actress to ever do so.
While her father appeared handsome and charming on-screen, Tatum O'Neal has described growing up with him as "very toxic" and by the time she entered her teen years, said her bond with her father was unraveling.
"I don't think he had any idea what to do with me, at all," she told "Nightline" anchor Cynthia McFadden in an interview promoting "Found". "I think he was fine when I was a little kid and he could take me around and we went everywhere together."
"I think as I grew breasts and kind of became a young woman, I think he just got weirded out and kind of started to struggle with me, it seemed, a lot," O'Neal continued. "I started to get unbalanced and I started to feel insecure, and I started to not know where to turn."
It was also this time when Ryan, now divorced from Tatum's mother, began to date a series of high-profile Hollywood women, including actresses Anjelica Huston, Bianca Jagger and then Fawcett, who he was with until 1997.
"He is getting older, has battled leukemia," Tatum reveals on the show of why it was Fawcett who, in the end, brought them together. "And how would I feel if my father were to get sick or die? Would I be OK? And I realized I wouldn't be OK. So I knew I needed to make an effort."
Both Ryan and Tatum told "GMA" the effort has been a struggle that, even today after the series has stopped filming, they continue to confront.
"I'm sensitive and I wish I was less sensitive," said Tatum. "But it's a nice feeling to feel that I have a parent and that we've done this show."
"It's challenging but it's worth it to have her back in the fold," Ryan said of his daughter. "She's still my little girl."
ABC News' Lauren Effron and Steven Baker contributed to this story.