According to the insider, Lauren and Devin were "on and off for a couple of months" before deciding to split once and for all.
"It's hard for Lauren right now because she really loves Devin, but it just was not working and they ultimately decided to split up," the insider added.
"They very much still love each other and are trying to figure out how to move forward. It's complicated and confusing as with all relationships. There wasn't one specific moment that defined them taking some space from each other."
Lauren and Devin's breakup probably comes as a surprise to fans given the blonde beauty gushed about her relationship and business-partner dynamic with Devin in July while they were promoting their new Dear Rose wine in Los Angeles, CA.
The last photo Lauren, 28, shared on Instagram, however, was all the way back on July 8. She also apparently stopped following Devin on social media.
Lauren and Ben got engaged on The Bachelor's Season 20 finale, which aired in March 2016, but after starring on Ben & Lauren: Happily Ever After? on Freeform, they announced their breakup in May 2017.
The former flight attendant moved from Denver, CO, to Los Angeles once things didn't work out with Ben, and that's when she says she reunited with Devin, whom she had met on Tinder before competing on The Bachelor.
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"I don't think I've shared before but I only met up with one person from the app and it was him," Lauren wrote to fans on Instagram during an October 2017 Q&A session.
"We hung out for a while but more as friends but always got along really well. Fast forward two years later when I moved back to L.A. we hung out to catch up and things just kinda happened after that."
Back in May, Lauren gushed to Us Weekly about how understanding and "supportive" Devin was of her involvement in Bachelor Nation.
She said she never gave him enough credit but he was such "a champ" about her life in the spotlight and constant chatter about her failed engagement to Ben.
However, Lauren was openly cautious about moving too fast with Devin given she went through heartbreak last year.
"I've always been someone who maybe jumps into things a little too quickly and I fall really fast," Lauren told Us in early August.
"And I always had this idea that I was going to be married by this age, kids, and this was going to be my plan -- and now, I mean, I'm almost 29 but I don't really have a timestamp on anything anymore, which is nice... I think going through the past and my past engagement and The Bachelor has made me want to just take things a little bit slower and not rush anything."