The news comes just days after they attended Comic-Con with their Riverdale co-stars. Things didn't appear out of the ordinary during their Hall H panel on Sunday, where Sprouse and Reinhart were seated next to each other and kept things professional backstage.
An eyewitness tells ET that the pair kept their distance at a party the night before. "They were both at Entertainment Weekly's Comic-Con party on Saturday, but not together," the eyewitness says. "Lili spent most of the night with her female co-stars, Camila [Mendes] and Madelaine [Petsch] and Britt Robertson, while Cole was on the other side of the party, hanging out with different friends and vaping."
Sprouse and Reinhart also stopped by ET's Comic-Con suite for an interview with ET's Leanne Aguilera on Saturday, where they assured fans that their Riverdale characters, Jughead Jones and Betty Cooper, were still "going strong." Though they weren't seated next to each other, fans couldn't help but notice their flirtatious behavior during the interview.
"I think they are going strong," Sprouse said, revealing that with Jughead at prep school in season four, "he's only back in Riverdale on the weekends."
That distance "will probably cause some stress," Reinhart noted.
"I think that is going to inevitably put stress on the relationship between Betty and Jughead," Sprouse conceded. "I think it might be a little bit tense. They might fall, turn away from each other, only to come back together way stronger. I think they're gonna be really good."
Sprouse, 26, and Reinhart, 22, had kept their relationship private from the beginning, but started to open up about their romance more in the past year.
"It's not something that we hide, or it's not something that we show off," Sprouse told GQin February. "It's just something that exists."
The next month, Sprouse opened up about the most romantic thing he had done for Reinhart.
"I really like the road-trip date. I took my girlfriend on a date where we drove to this location deep into Canada, and I surprised her with a big hot-air balloon adventure, which was quite a bit of fun," he said. "I like traveling quite a bit. I like road-tripping. Those grand experiences always end up yielding the greatest memories -- and the greatest romances."
The Five Feet Apart star continued, sharing that his love language is "quality time." "I'm not really the type of person that likes going to a movie and sitting in silence," he said. "Maybe a little breaking and entering! Some photography! Who knows?"
In an October 2018 interview with Teen Vogue, Reinhart gushed over her "adventures" with her then-boyfriend. "He takes me to places where I'm like, 'How did you find this?'" she said. "He's made me see these things that I would have never seen otherwise. It's escapism, which is so beautiful and wonderful."
Sprouse and Reinhart's romance appeared to have the support of their Riverdale co-stars, including Reinhart's onscreen mom, Mädchen Amick.
"It's great. I mean, they didn't talk about [their relationship] the entire time, until just recently," she told ET last year. "So, it's nice that they're able to now, like, be public with it, so it's not so under wraps."
"But at the same time, they're in complete control of what they want to share and how they want to share it," she added. "Behind the scenes, they're so sweet with each other and they're both just exceptional people."
See more in the video below.