Diddy Spent New Year's Eve With Cassie?

No one should be surprised by this.  After spending Christmas vacay with his baby mama Kim Porter and all the kids in St. Barts, and looking pretty cozy with Kimmy on the yacht, Diddy bounced right back to Cassie for New Year's Eve.

We've got the deets on them ringing in the New Year together in Vegas when you read on...
Who are we to judge--maybe these ladies have an "understanding".  Or maybe they're ok with looking foolish to the masses on such a public level.
Anywho, Diddy hit up Marquee Club at the Cosmopolitan Hotel after his own NYE hosting gig at LAX nightclub.  He went over to the BING sponsored party at the new Cosmopolitan Hotel to kick it with his homies Jay-Z, Kanye, and everyone else who was there.  And, of course, he had Cassie on his arm.
The event organizer confirmed to us that Diddy indeed spent the whole night with his "girlfriend" Cassie as they partied alongside their friends in private booths.  The organizers confirmed:

"The party wound down after 5:00 AM on New Years Day, but not before Diddy and his girlfriend Cassie made a final stop to say "Hi" to his friend Erick Morillo in the main rooms DJ booth, Morillo proceeded to play Diddy's "Hello Good Morning" and the crowd and the camera's went crazy.

By the way, Jay took some time shortly after the clock struck midnight to wish the crowd--and his wife--a Happy New Year.  The organizers tell us the inside deets of the party:

Following Jay-Z and Kanye's second performance of the evening, Jay asked comedian Aziz Ansari to join them in the DJ booth and entertain the crowd with a "New Years Eve joke." Ansari said no, but Jay wouldn't relent and eventualy Ansari took the mic and got a few laughs.  But not before Jay, Kanye and Rhianna were joined by Beyonce in the booth, at which point Jay stopped the music to wish happy new year to everyone in the room and to his wife "B".

Sweet!