Just days after they put what was up until that point a rumored romance on display at the Billboard Music Awards, Taylor Swift is supposedly confronted boyfriend Calvin Harris about swirling allegations of his infidelity.

RadarOnline reports just hours before he and Swift looked like the perfect couple at this month's award show, 31-year-old Harris was seen leaving a Las Vegas pool party with a "beautiful brunette."

According toThe Mirror, all the growing chatter has proven enough for Swift to question Harris about the "mystery woman" and wonder if he truly has been able to put his one-time playboy lifestyle behind him. Even Swift and Harris are rumored to have started dating while he still had a girlfriend.

Both Swift and Harris also have a reputation of dating other high profile celebrities, with the 25-year-old "Shake If Off" singer having gone out with John Mayer, Jake Gyllenhaal, Harry Styles, Corey Monteith and Joe Jonas.

In the past, Swift has used some of her breakups as motivation for new music, including the "I Knew You Were Trouble" song she once clearly recorded with Mayer in mind.

"Long were the nights when my days revolved around you," Swift opens the song before lamenting throughout how she should have known from the start that the reportedly womanizing "Your Body Is a Wonderland" singer would be trouble.

Meanwhile, Harris been romantically linked to fellow musicians Rita Ora and Ellie Goulding.

At the Billboard Awards, Swift bagged eight trophies, including top artist, and at one of the event's after-parties she and Harris were seen celebrating her night by openly making out.

Swift is also known for such hits as "Everything Has Changed," "Highway Don't Care," "White Horse," "Back to December," "We Are Never Getting Back Together," and "You Belong With Me."