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Lili ReinhartandCole Sprousemay have broken up, but they are keeping things as professional as possible on theRiverdaleset.

“Their friends didn’t really expect them to last in the long-run,” a source tells PEOPLE.

“At the end of the day, their personalities are very different and their lifestyles often clashed,” the source adds. “Things have felt super heavy in the relationship for a while, and it got to be too much. They’re both very professional though and trying to be as amicable and friendly as possible.”

Reps for Reinhart, 22, and Sprouse, 26, did not immediately respond to PEOPLE’s request for comment.

News of Bughead’s real-lifebreakupcame earlier this week, after the two were seated next to each other atRiverdale‘sHall H panel at San Diego Comic-Con.

Reinhart appears to be taking the split in stride, however,joking on Instagramabout being seated next to Sprouse and their costarKJ Apa.

Lili Reinhart and Cole Sprouse at Comic-Con on Sunday.Richard Shotwell/Invision/AP/Shutterstock

Lili Reinhart, Cole Sprouse

“Please don’t put me between these two ever again,” she captioned a photo of the three onscreen BFFs.

Throughout their two-year relationship, both Reinhart and Sprouse have been vocal in their desire to keep their romance private.

Broadimage/REX/Shutterstock

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“I think that in many ways it’s offensive and an invasion of privacy, but it’s also a badge of honor because it means you’re creating a chemistry onscreen that is so understandable that people want to see it in real life, which is flattering from a professional perspective,” he said, adding, “I just never talk about it because it’s not anyone’s right to know.”

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Reinhart toldHarper’s Bazaara few months later, “I’m not okay talking about my relationship. I’m not going to tell you my love story. That’s just not appropriate right now.”

But despite withholding details on their romance, the coupleseemingly confirmed their relationship statuswhen they walked the 2018 Met Gala carpet together. The pair also attended this year’sCamp-themed Met Galatogether just two months ago and have routinely sharedphotosofone anotheron social media.

The duo have been busyfilming the fourth season ofRiverdale, which will return to The CW this fall.

source: people.com