And according to her personal website, Caitlin is a model, fitness and health enthusiast, and the CEO and founder of Caitlins Vine Of Bravery dog rescue. Caitlin is also the founder of Make Him Famous Ministries.
The source said the religious pair are "interested in getting to know each other more."
"They run in the same circles and are definitely talking and run in the same circles," the source explained to Us.
"They like each other and want to progress slowly and see where it goes, but nothing is official right now."
Earlier this month, Caitlin shared a selfie with Luke as well as two other photos of the couple on Instagram in which they were both bundled up at a rink.
"Taking our ice skating skills to the Olympics," Caitlin captioned the photo.
Caitlin reportedly dated Justin from 2008 to 2009 but attended the singer's wedding to Hailey Bieber in October 2019.
As for Luke, he fell in love with Hannah on The Bachelorette's fifteenth season, but his world came crashing down on him at the time of her overnight Fantasy Suite dates.
Luke appeared The Bachelorette as a born-again virgin. Despite previously abusing sex and alcohol in his teen and college years, Luke had abstained from sex for three or four years prior to going on the show.
Hannah was smitten with Luke in the first few weeks of the show, but she ultimately eliminated him before the overnight portion of their Fantasy Suite date in Greece.
Hannah sent Luke packing because she felt judged and shamed by the religious bachelor during their discussion about premarital sex in which Luke questioned whether Hannah had slept with one or more of his competitors.
Luke was shown saying the marriage bed should be kept "pure" during their date.
"I just want to make sure you're not going to be sexually intimate in your other relationships here. I totally have all the trust in the world for you, but at the same time, I want to know we're on the same page," Luke told Hannah at the time.
"If you told me you're having sex or you had sex with one or multiple of these guys, I would be wanting to go home, 100 percent."
But instead of being on the same page, Hannah flipped out on Luke and told him to leave. Hannah admitted she had sex in a windmill -- twice (although she later admitted on After the Final Rose it was four times with Peter Weber) -- and even flipped Luke her middle finger on his way out.
But Luke returned to the Final 3 Rose Ceremony to fight for Hannah and hopefully win her back -- only to get brutally rebuffed by Hannah again in front of Peter, Tyler Cameron, and Jed Wyatt.
Before The Bachelorette: The Men Tell All aired in July 2019, Luke took to Instagram to explain why he seemed bewildered and disappointed after learning Hannah had sex while filming the show.
"In my hometown date I brought Hannah to a bible study with my college church group, where I shared my story of how God transformed my life and gave me a desire to live my life for him in obedience, that included waiting until marriage for sex," Luke shared in an Instagram post at the time.
"Hannah on the date, stands up and tells the group her story of how she was convicted to live a life in pursuit of Jesus. She also told them that she wasn't going to use the fantasy suites for sex but for conversation, no matter how @abcnetwork made it look."
And then during The Men Tell All, Hannah clarified she had never planned on having sex in the Fantasy Suite -- that it just happened when it felt right -- but it was not Luke's business to ask her about it or anyone else's business to know.
"Are you really telling me that you never said, 'Don't judge me about the Fantasy Suites, because I won't be using them for sex?'" Luke asked Hannah.
"I did not say that. Fantasy Suites aren't used for sex. You didn't have one so maybe you don't know, but Fantasy Suites aren't used for sex," Hannah replied.
Hannah got engaged to Jed during her season finale but dumped the aspiring country singer five weeks later after discovering he had lied about the extent of a romantic relationship prior to appearing on the show. She remains single today.
Meanwhile, Peter's season of The Bachelor is currently airing on Monday nights at 8PM ET/PT on ABC.