jbeiber052012_01_X17.JPGBut where was girlfriend Selena Gomez?!

If you watched the Billboard Music Awards last night, you might be wondering about the mystery brunette who accompanied Justin Bieber to the show.

It turns out she's Cady Eimer, an 18-year-old Virginia high school student who has been asking Biebs to be her senior prom date for several years now. Justin was unable to go to her hometown, so he had an even better idea -- take to her to Las Vegas for a star-studded awards show!

"I couldn't make it [to prom] so I said I need you to fly to the Billboard Awards and you can be my date," he told People. "She's a big fan and I thought it would be fun." Aww!

But seriously, what's going on with Selena? We know she was busy shooting Spring Breakers this weekend, but you'd think she'd want to come out to Sin City with her boyfriend! A few days ago Justin allegedly tweeted, “thank you for the time i had with you but i have to move on now," and while the message has since been removed, we do think it's a bit fishy! Bieber's manager Scooter Braun has denied that Justin posted the tweet, but he didn't comment on the status of Jelena's relationship either. Hmm!