Sanni Honnold knew what she signed up for.

It was a cacophony of racing hearts and gnawing teeth as Alex Honnold ascended the world's 11th tallest building this weekend.

With no ropes, harness, or safety net, the American rock climber scaled Taipei 101, a 1,667-foot skyscraper in Taiwan.

The record-breaking climb was broadcast live on Netflix to millions of viewers. Crowds also gathered to witness the stunt in the flesh.

Watching from (safely inside) the 60th floor was Alex's wife, Sanni, who gave her husband a thumbs up as he passed her window.

When Alex reached the top of the skyscraper, Sanni greeted him on the roof with a laugh and a hug.

Then, as casually as one might discuss a beach day, Sanni told Alex she had been worried it was too hot or windy for him.

Watch: Alex Honnold greets his wife Sanni at the top of Taipei 101. Post continues after video.

Sanni, who works as a life coach, is also a climbing enthusiast. But even she admitted she was glad Alex was the one who scaled Taipei 101.

"When you really love someone, and you think that they might be stressed, you're kind of like, 'I wish I could take their place,'" Sanni said at a press conference after the climb.

"But in this case, I was like, 'Thank God I'm not him!' she added.

Despite any fleeting anxieties, Sanni had faith that Alex would succeed.

"I knew the second he left the ground it would all just kind of… get quieter, kind of be a little bit more of an internal experience, and then just be joyful," she said.

"So, I was really happy when it just started. There wasn't any waiting. He got to do what he wanted to do."

Alex Honnold successfully free climbed the Taipei 101 skyscraper. Image: Instagram/@alexhonnold

Long before he met Sanni in 2015, Alex fell in love with rock climbing.

In 2017, he became the first person to free climb El Capitan, a 3,000-foot granite wall in Yosemite National Park. It was a feat that became the subject of the 2018 Oscar-winning documentary, Free Solo.

The climb (and media frenzy that followed) coincided with what should have been the honeymoon phase of Alex and Sanni's relationship. The reality was far from it.

"I could tell the filmmakers were frustrated by my presence — because, let's face it, relationships complicate things," Sanni told Outside in 2021.

"Even Alex came to me at one point wondering if we should break up," she continued.

"He worried that I would get in the way of his climbing and that he needed to choose: love or greatness. I remember asking, 'Why not both?' And so we forged ahead."

When the documentary aired a year later, Sanni was faced with a wave of commentary about her relationship.

Some people accused her of getting in the way of Alex's ascent, while others insisted he would never love her as much as he loved climbing.

"I remember holding my breath and thinking, 'Can't some things be equally important?'," Sanni said.

As hard as that period was, Sanni believes it prepared her and Alex for the life they have created.

"We fell in love in front of a film crew, knowing that if it didn't work out, we'd have complicated many people's lives for nothing," she said.

"We had to discuss not only the prospect of death, but what we each needed to truly feel alive. The overwhelming sea of press and publicity taught me to let go of what other people think of me and my relationship."

Fast-forward to today and Alex, 40, and Sanni, 33, are married with two young girls, June, and Alice, who are almost four and two respectively.

Alex and Sanni with their kids. Image: Instagram/@sannimccandless

Ahead of his most recent climb, Alex told CNN that his family is his priority.

But, even with kids, his passion for free climbing hasn't slowed down.

"I didn't want to die before, and I still don't want to die now," he told Imagine5.

As of right now, Alex's kids don't really know what their dad does.

"I don't think they know what climbing is when we're bouldering, kind of climbing small rocks," Alex told CNN. "They'll play in the forest… but I don't think climbing means anything to them yet."

Still, the 40-year-old would rather his girls follow in his footsteps than "get into partying," which he argued has potential dangers of its own.

In a 2022 interview with Fatherly, Sanni was asked how she felt about Alex returning to free climbing after becoming a dad. She stressed that she was in full support.

"It's still clear that that's what he needs," Sanni told the publication. "Alex is the happiest and best version of himself when he gets to spend a lot of time outside and when he is climbing. He's so cranky when he doesn't get to climb."

The mother-of-two went on to say she is "here to problem-solve, support, be optimistic, be positive, make sure everything's in line."

"And Alex does that for me in my projects and in my life and my work. That's what makes us a good team, I think."

Sanni's support for Alex has been unwavering from the start. She has always known the risks involved with his endeavours, and has stood by him even as their family as grown.

Not every relationship would survive this.

"Sometimes passions and risk tolerance can change over the duration of a relationship," psychologist Carly Dober told Mamamia.

"People tend to mellow out with age, and adult life can be very busy, limiting and reducing opportunities to engage in risk-taking behaviours."

Others, like Alex, "never slow down." And while Sanni has accepted that lifestyle, some onlookers have found it a hard pill to swallow.

"I think there is an unspoken expectation that you don't live for yourself, we live for the people who are around us," Dober said.

"If we have children, we live for them, and we should be around to see them grow for as long as we can if we can.

"People have opinions about Alex's behaviour because they couldn't imagine doing that themselves or doing it to their family," she added.

At the end of the day, it comes down to "different belief systems" across relationships. The key, Dober said, is having your "eyes wide open" from the start.

"In this instance, Alex has been doing these climbs forever and has never indicated he is going to stop," she said.

Sanni knew what she was getting into, and she has loved him unconditionally every day since.

Feature Image: Netflix.