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The romance that blossomed between two of our favorite self-described nerds, Josh Groban and Kat Dennings, has come to an end.

"It was a mutual breakup," an insider tells E! News. "They are still friends and care about each other, but it's not the right time for them now as a couple."

E! Was the first to report the pair were dating back in October 2014, after they attended the Carousel of Hope Ball in Los Angeles together.

"They were so cute together!" a source told E! At the time. "They were adorable on the carpet. She was whispering in his ear a lot and they seemed really happy."

Kat, 28, later admitted to Ellen DeGeneres that she was seeing the 33-year-old singer, explaining that he'd first caught her eye on social media.

"He's very witty on the Twitter, and I saw his little Tweets sometimes," she said on "The Ellen DeGeneres Show."

According to E!, it was Beth Behrs -- who stars alongside Kat in "2 Broke Girls" -- that introduced the two.

"[Beth] always talked about how great he is and they've been friends for years, and she thought we were both, you know, nerds," Kat dished. "So there, she was right."

Speaking to People, Beth marveled at what a great couple Kat and Josh made. "They're in this crazy business, they're both very calm and mellow and wonderful. And he treats her like a princess, and it's amazing," she said.

The adorable pair frequently chatted about one another in public, too. Last year, Josh admitted Kat had gotten him obsessed with "RuPaul's Drag Race," while Kat giggled through an anecdote on "Ellen" about the time Josh made up a song about her while she was steam cleaning the carpet.

In February, Kat was noticeably absent from Josh's arm at the 2016 Grammy Awards, where his last release, "Stages," was up for Best Traditional Pop Vocal Album. (Tony Bennett and Bill Charlap ended up taking the prize for The Silver Lining: The Songs of Jerome Kern.) She did join him for Clive Davis' pre-party, though.

On the bright side, both stars have plenty of other things on their respective plates these days. In October, Josh stars in the Broadway show, "Natasha, Pierre & The Great Comet of 1982," an electropop musical based on 70 pages of "War and Peace." Kat's hit "2 Broke Girls" returns to CBS for its sixth season Oct. 10.