Gaga and Kinney -- who even posed for a few selfies with fans on Friday --announced that they were "on a break" in July 2016. The two met on the set of her "You and I" music video in 2011, and got engaged on Valentine's Day in 2015.
He went backstage with his squad after the show. Y'all, please get back together. My otp.
ET caught up with Kinney in March, when he opened up about his dating life after his breakup with Gaga.
"My dating life is through Chicago Fire," the actor quipped. "I live vicariously through my character."
"I don't think I have a type. I think it's more of an energy," he explained. "I think of compatibility as the intangibles of something, and someone that you meet and connect with, and someone you can laugh with, and maybe share a [similar] sense of humor, then things go from there."