What happens in Vegas doesn't always stay in Vegas.
Of course, the former One Direction member didn't disappoint in the fashion department. But the Don't Worry Darling director certainly gave her man a run for his money as she stepped out in a fabulous baby blue blazer that she styled without a shirt and matching trousers.
In fact, Twitter user Genna Baker captured video footage of the Booksmart director looking effortlessly chic as she was escorted from the backstage area to her seats.
Moreover, a concertgoer exclusively tells E! News just how much fun Olivia had at Harry's show.
"She was so happy and dancing all night!" the eyewitness dishes. "It was very cute. She was singing along to almost every song...and having a good time with the people she was with."
The insider adds that Harry was totally back in his element while performing at his sold-out show at the MGM Grand Garden Arena.
"The energy in the room was electric!" the eyewitness shares. "You could tell how much he missed being on stage. It was one of the best shows I've ever been to!"
According to the concertgoer, Harry did have a "slight mishap on stage" but he bounced back like a pro.
"He slipped and fell for a second," the eagle-eyed observer notes, adding, "He recovered and then sprayed the crowd with water."
All in all, the eyewitness reveals Harry's first tour performance was one to remember, especially since he played hits like "Sign of the Times," "Watermelon Sugar," "Kiwi" and One Direction's "What Makes You Beautiful."
While the singer and Olivia, who confirmed their romance in January, haven't publicly shared details of their Las Vegas night out, it's clear they have undeniable chemistry.
Just last month, a source told E! News just how special their connection is.
"They are very supportive of each other's careers and want to be together wherever they can," the insider said. "They seem very happy and have a great relationship. They have a close circle of friends and a fun social life, too."
The source added, "They click and they just want to be together. They make each other a priority no matter what. It's not hard because they are crazy about each other."
Relive their whirlwind romance here.
—Reporting by Holly Passalaqua