The "lovely" singer's rep tells us ... "We can confirm Billie and Jesse did split amicably and remain good friends. All cheating rumors are false. Both are currently single."

The breakup marks the end of a short-lived relationship ... we first saw Billie and Jesse hanging out -- and making out -- back in October, and in November they went Instagram official.

But Billie and Jesse, the lead singer for the band The Neighbourhood, had not been seen together in public since last month when they went to Coachella.

Billie seemed to signal trouble with the relationship earlier this month, when she showed up to the Met Gala without Jesse, dressed in all black.

While Billie was reportedly seen cozying up to "Love, Victor" actress Ava Capri at a Met Gala after-party, we're told neither Billie nor Jesse was unfaithful when they were dating.

Still, it's unclear what led to the split ... Page Six was first to report it.

Remember ... Billie and Jesse first sparked dating rumors in October 2022 when a viral video showed them walking out of a haunted house together, holding hands.

TMZ broke the story ... the Hollywood Horror Nights outing came the night after Billie and Jesse went on a dinner date at a famous Los Angeles vegan restaurant, where they also looked like a couple.

A couple days later, Billie and Jesse showed off some PDA, kissing in front of cameras.