Niall Horan hangs out with Harry Styles' ex-girlfriend Taylor Swift at a 2014 London concert

According to some eyewitness reports, Niall Horan might have violated the "bro code" over the weekend. The One Direction singer was spotted at London's O2 Arena supporting bandmate Harry Styles' ex-girlfriend Taylor Swift at one of her concerts. Thought the two were just hanging out, Directioners were not too happy to see Niall with Taylor!

It should also be said that Harry and Taylor broke up over a year ago and though it was a messy break up, the two are now friendly again and have hung out since. So Niall hanging out with Taylor shouldn't be that big of a deal.

"Taylor was happy to sort Niall some Access All Areas passes and even had drinks with him before the show," an insider said. "They met through mutual friend Ed Sheeran. Niall seemed like a genuine fan of Taylor's music."

The source added: "However, he smirked when she performed 'I Knew You Were Trouble' which was rumored to be about Harry."

Niall, recovering from a recent knee surgery, didn't mention attending the Swift concert on Twitter however. Perhaps he was hoping to avoid backlash from fans? Too bad the drama happened anyway!

After the concert, he did take to Twitter to post his excitement over playing the Metlife Stadium during One Direction's 2014 world stadium tour entitled "Where We Are."

The Irish heartthrob tweeted: "Watching the Super Bowl! And all I can think of is! "I can't believe we are playing that stadium in the summer" mind blowing s**t."