When Hunter first met Melissa, he leveled with her about his past, including the tragic deaths of his mother, sister and brother, decades of struggling with addiction and a turbulent divorce. And yet, they are ready to face the future together.
"I instantly fell in love with her. And then I've fallen in love with her more every day," Biden, 49, said.
Hunter's first call was to his father to share the happy news. Joe Biden thanked Melissa for "giving my son the courage to love again."
Hunter has three adult daughters from his marriage to his first wife, Kathleen: Naomi, 24; Finnegan, 19; and Maisy, 18. According to the couple, his daughters love Melissa and get along great.
Melissa is from South Africa, but recently became a naturalized U.S. citizen, a ceremony Hunter proudly attended.
Watch the full interview on "Nightline" THURSDAY, Oct. 17 at 12:35 a.m. ET on ABC.
Hunter is not hiding, he says defiantly, despite Trump's public claims to the contrary on Twitter and at his rallies.
"No, not at all," he said. "I'm actually having an incredible extended honeymoon with my beautiful bride."
"I would call it the honeymoon phase, definitely," added Melissa, who was also previously married. "Although, I have an inclination that I'm gonna be in the honeymoon phase for a very long time. ... Things have not been easy externally, but internally things have been amazing."
Melissa believes "the truth will prevail" in relation to the criticism her husband has received over his controversial position on the board of Burisma, an oil company in Ukraine, and described her husband as "an incredible human being" who "very much cares about his country and his family and his friends and his children." Biden reportedly made $50,000 a month to sit on the board. Melissa also welcomed an investigation.
"Sure. Why not? I mean, nothing's gonna change. I mean, I would probably -- I think it would probably be a waste of tax payer's money. And seeing as though how many of -- how many investigations can be done? But if it would bring peace of mind to whoever needs peace of mind brought to this, I know we have peace of mind, we're okay, we've -- we live in truth, so sure."
Trump's obsession with the position came into clear view after the news of a whistleblower complaint detailing a July call by the president to Ukrainian leader Volodymyr Zelenskiy, when he repeatedly asked for an investigation into the Bidens.
Despite being at the center of a political maelstrom, their daily life is innocuous, as Hunter describes it:
"I talk to my dad every day. I live my life in the open," Hunter said. "I get in my car in the morning and I go down the road and I get coffee. And I go to the same place for lunch with Melissa. And I go about doing my business and my work, and I come back at night. And we watch -- you know, Netflix, and then we do it all again in the morning, just like anybody else."
"And the reason I'm able to do that is because I am absolutely enveloped in love of my family," he added.
Biden has sought out treatment for substance abuse issues more than seven times. His late brother Beau personally took him to his first rehab session. It was a positive test for cocaine that got him discharged from the Naval Reserves in 2014.
Now, Hunter refers to his wife Melissa as his "redemption" and his "protector." When asked if she was worried about her husband’s sobriety with so much public pressure, Melissa firmly stated: "No. He's incredibly strong."
"You don't want to live in the worry of it because then you're feeding the beast," Hunter said. "I have no answer other than this: you gotta live in the connections that you have to healthy things. And I have so many of them."
He likened seeking treatment for addiction to doing the same for a "terminal illness," musing that tabloid headlines describing him as going "in and out of rehab" send the wrong message.
"Boy, if you have to be embarrassed about asking for help, you know how much harder it makes for people without the means or the ability or a job that's not gonna tolerate it?" Hunter asked. "Or a husband or a wife that doesn't want you to go in and out? That feels embarrassed by it? So we all gotta start talking about it differently. ... It is terminal. And so I think that we owe people that are seeking help the empathy, but also a level of compassion."
"Every time everybody that I know that goes back in to try to get help -- whatever way that it is -- it's a courageous act on their part, it really is," he added. "It's an act of humility. It's an act of admission and it ain't easy."
A series of tragic events have shaped Hunter Biden’s life. In 1972, when he was 2 years old, his mother, Neilia, and his sister, Naomi, were killed in a car crash. He and Beau were also in the vehicle and were severely injured.
The brothers were close all their lives, but in 2015, Beau, the former attorney general of Delaware, died of brain cancer. Hunter later dated Beau's widow, Hallie, another talker for the tabloids in addition to battling alcohol and drugs and going through a public and tumultuous divorce from his first wife.
He is currently facing a paternity and child support lawsuit from an Arkansas woman named Lunden Roberts alleging Hunter is the father of her child. He denies that claim.
Hunter's life is often on display in tabloids, but in the interview with ABC News' Amy Robach he wanted to share his side of the story.
"I've gone through my own struggles … like every single person that I've ever known; I have fallen and I've gotten up," he said. "I've done esteemable things and things that I regret. Every single one of those things has brought me exactly to where I am right now, which is probably the best place I've ever been in my life."
Hunter Biden had been noticeably absent from the campaign trail with his father, one of the front-runners for the 2020 Democratic presidential nomination four years after he served as vice president. He and Melissa made their first public appearance with his father last Friday at a fundraiser in Los Angeles.
He had previously avoided the spotlight, saying, "This is not a family business."
"Everybody kinda thinks that somehow -- you know, whether it's a compliment that we're like the Kennedys or whether it's a backhanded compliment like you're the Trumps -- my dad has a job, but that does not mean that I had ever had any plans to go do rallies and talk about Donald Trump's kids," Hunter said. "And I never will."
For now, Hunter seeks refuge in his art studio at home, where he likes to paint.
"It literally keeps me sane," he says.
When it's pointed out that there is a TV in the room, he chuckles, "You know, luckily I don't get cable down here."