While the two buddies have both been romantically involved with Demi Lovato, they don't seem to be letting that get in the way of their bromantic relationship!
However, we can't help but wonder if the X Factor judge would have a Heart Attack if she knew her current flame and former flame were BFFs!!
Kaley Cuoco certainly seemed surprised to see the two together as she sat right behind them with her boyfriend Ryan Sweeting!
Her expression pretty much sums up how we feel about the whole thing. So confused, yet so amused!!
P.S. CLICK HERE to see what other celebs made an appearance at the U.S. Open!
[Image via Joel Ginsburg/WENN.]