Robert Pattinson has been openly dating Tahliah Barnett, and now the "Twilight" star's ex, Kristen Stewart, was reportedly mocked at the concert of the singer more popularly known as FKA Twigs.

According to a report from Hollywood Life, the dissing incident allegedly took place during the English electro-pop singer's October 9 concert in Bristol, United Kingdom.

An audience member suddenly yelled: "F**k Kristen Stewart."

As a response, the edgy singer did not say anything, but let out a visible smirk.

However, an eye witness during the concert clarified that FKA Twigs did not intend for the smirk to be misinterpreted as rudeness.

"The smile was not out of anything remotely close to smugness," the insider said, reported by Hollywood Life,

The source added: "It must be pointed out, more like the astonishment and disbelief that comes from watching that gung-ho chancer in maths answer back to the dragon of a teacher we all had."

Robert Pattinson has been dating Tahliah Barnett against the demands of die-hard "Twilight" fans. Some hardcore fans have even gone to the extent of posting racist comments on the English singer's page.

According to a report from Celebuzz.com , the electro pop musician took to Twitter to indirectly speak about the bullies who are not in favor of her as the actor's girlfriend.

FKA Twigs posted: "I am genuinely shocked and disgusted at the amount of racism that has been infecting my account the past week."

Robert Pattinson's rumored girlfriend added: "Racism is unacceptable in the real world and it's unacceptable online."

Robert Pattinson dating Tahliah Barnett reports has been on-going for weeks. According to a report from Daily Mail, the hunk actor allegedly "couldn't keep his hands off" the British singer.

Robert Pattison dating Tahliah Barnett is the actor's first seemingly serious and publicized relationship after he broke up with "Twilight" co-star Kristen Stewart last summer.