"For the rest of my life, it's you," he captioned a Thursday night Instagram post containing a gallery of photos from the couple's engagement shoot.
Congratulatory comments quickly poured in from other Bachelor Nation alums after Nick's posting -- including one from former The Bachelor bachelorette Vanessa Grimaldi, who got engaged to Nick at the conclusion of his 2017 season of The Bachelor.
Nick, 42, and Natalie, 23, reportedly first became romantically involved in 2019 but attempted to keep their relationship private for more than a year and didn't go public until after widespread reports that they were dating surfaced in January 2021.
Nick and Natalie's engagement isn't unexpected given the couple has been living together and openly talking about the possibility of getting married and having children for some time.
"We're talking about it more," Natalie replied when asked about the possibility during a joint interview with Nick on the "Call Her Daddy" podcast in June 2022.
"We're having those conversations that everyone is scared to have, but they're definitely needed. We talk about finances, children, where we want to live, and things like that. We are definitely opening up and talking about those things more. We're not not trying, we're not trying either. We're just living life."
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Nick also noted Natalie was "playful" when they discussed getting engaged and she had given him some helpful tips and hints.
"She asked me once [about an engagement], because she's very playful. But great, she's giving me the information I need to be successful," Nick said.
"I love that for me. She was like 'Is this too much?' And it wasn't. She walked the line carefully and told me exactly what you want and where you're at."
Nick suggested he was relieved that Natalie showed him what she liked and how she'd envision his proposal.
"Now I know, and this is good to know, but I don't feel pressure," Nick explained on the podcast.
"As a guy, you get to a place where you don't want to have to reassure your partner that you want to marry them or want to get engaged. She wants to tell me things, but we both have a level of wanting it to be romantic and a surprise, rather than knowing today is the day."
Nick reportedly even got emotional when talking about his strong feelings for Natalie and confessed that, for the first time in his life, he would "not be okay" if Natalie left him.
According to the former The Bachelor star, he had typically anticipated a breakup in each of his prior relationships but Natalie had made him feel "so safe."
During the interview, Nick also revealed he and Natalie initially met through friends but she was the one to make the first move.
"She slid into my DMs. It was very romantic," Nick recalled with a laugh, adding that he first met her when he was with some of his friends in New York.
Nick starred on Season 21 of The Bachelor in 2017 after several prior attempts to find love on The Bachelorette and Bachelor in Paradise didn't work out for him.
Kaitlyn ended up giving her final rose and getting engaged to personal trainer Shawn Booth, whom she split from in November 2018 after three years of being together. (Kaitlyn is now engaged to The Bachelorette Season 14 alum Jason Tartick and planning their wedding).
Nick continued his search for love on reality television following his split from Kaitlyn through a stint on Bachelor in Paradise, but when a romance with Jennifer Saviano didn't work out, ABC selected him to star on The Bachelor's 2017 season.
Nick got engaged to Vanessa at the end of his season, but their romance kicked off with more challenges than the average The Bachelor couple to come out of the show given Vanessa had been living in Canada and Nick preferred to stay in the United States.
Shortly after getting engaged, Nick also competed on Dancing with the Stars, which soaked up a lot of his free time and energy.
Nick and Vanessa split in August 2017 and Nick seemingly never entered another serious relationship until Natalie in 2019.
As for Vanessa, she announced her engagement to Canadian businessman Josh Wolfe in August 2020, and the couple got married on August 2021 in their hometown of Montreal, Canada.