The boyfriend of social media star Bianca Devins may have flipped out when she kissed another man while attending a concert in Queens on Saturday night, a report said.

Oneida County District Attorney Scott McNamara on Tuesday revealed the possible motive for why Brandon Andrew Clark, 21, allegedly murdered his girlfriend.

“The belief is that she kissed somebody at the concert and that’s what upset him,” according to Utica’s WKTV.

It’s unclear which concert the couple attended, but afterward they drove back up to Utica, where Clark allegedly snapped, slitting Devins’ throat and posting a grisly photo of her to Instagram, police have said.

“I have a very hard time understanding how anybody can justify taking another young person’s life because they kissed somebody else,” added McNamara.

Clark, of Cicero, called the cops on himself after allegedly murdering Devins, 17, authorities said.

When cops arrived, Clark cut his own throat, then posted a photo of his bleeding neck on Instagram.

He was rushed to a nearby hospital, where he’s recovering from surgery.

Utica police spoke briefly to Clark on Monday, but their conversations dried up once he got a lawyer, according to the report.