Thurston, 30, and Hersey, 27, made their red carpet debut together on Thursday. While being photographed, the pair shared a loving kiss.
The couple attended pal Stephen Lovegrove's First Noelle Ball, which was held at the Mavericks Beach Club in San Diego, California. Other Bachelor Nation stars in attendance included Cassie Randolph and her boyfriend Brighton Reinhardt, Hannah Godwin and her fiancé Dylan Barbour as well as Katie Morton and Tammy Ly.
On Thurston's Instagram Story, she shared a selfie of the pair all dressed up before heading to the holiday party. The Washington native also posted a video of the pair sharing a kiss on the red carpet.
"When it's suddenly snowing in San Diego and your whole mood changes," the former Bachelorette captioned another video from the event. "Thank you @drlovegrove for the event of the year!"
After appearing as a contestant on Matt James' Bachelor season earlier this year, Thurston was named the Bachelorette for season 17. She ended her journey engaged to Blake Moynes, though the former couple announced their split in October.
"It is with mutual love and respect that we have decided to go our separate ways," their joint Instagram statement read. "We are so grateful for the moments we shared together and the entire journey that has unfolded this year, but we ultimately have concluded that we are not compatible as life partners, and it is the most caring choice for both of us to move forward independently."
"We ask for kindness and privacy as we both navigate this transition," they continued. "Both of us will forever want the best for one another and ask you to please support us in our decision."
On Nov. 23, a rep for Thurston confirmed to PEOPLE that she has been dating Hersey.
"It's known Katie and John became close friends post-season," the rep said. "John has been there for her through all the major changes in her life and they are excited to explore this newly found romantic connection."
News of Thurston and Hersey's relationship led Moynes, 31, to question whether "emotional" cheating occurred.
"You start to think about timelines. I know they spent a lot of time together and stuff, but there's just no way, I didn't have an inkling," he recently said on the Talking It Out with Bachelor Nation podcast. "I'm a very secure guy, a confident guy, and I give my trust out 100 percent, especially to the person I should be trusting the most. I really don't think there was any physical cheating there, but there's clearly emotional for it to transition as quickly as it did."
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Hersey later shut down the cheating allegations in an open letter on Reddit, saying it "hurts" to see people "build assumptions and throw around accusations based on very limited knowledge of a situation." He also reiterated that things were "always platonic" between them, even during Thurston's engagement.
"The boundaries of our friendship with respect to her ongoing relationship never even required addressing, because it was never a thought in our minds that we would ever be anything more. You guys — she was engaged. It is apparent that many of you misjudge how both her and I view that commitment," Hersey wrote. "Neither Katie nor I would ever cheat, push someone to cheat, or be involved in cheating. It is not in our nature. It is not acceptable. It is not okay."
According to Hersey, the couple knew "the optics of it all" would be "the only difficult part."
"To those of you that suggest we should have waited — I understand. I hear you. But try to understand what it's like for me, a regular guy, falling helplessly for his best friend, not being able to take her out for dinner because photos would likely leak and everybody would assume we were trying to foster some sort of secret and scandalous relationship," he added. "Our decision to come out publicly was a decision to pursue happiness in the way we wanted."