Not only did Rob not arrive with his girfriend/co-star Kristin Stewart, she didn't even show!

But OK reports that over 500 people, including the cast and crew (whom were each allowed to bring only one guest and show ID at the door) attended the big bash, thrown by Eclipse director David Slade at the Vancouver Aquarium Saturday.

Rob arrrived solo at 10pm, and many of the party-goers expected Kristen, who still has another week of shooting left on the show, to stop by soon after. “It’s not like she has anything else to do in Vancouver,” said one guest. But Kristen was a no-show and Rob himself ducked out after only 45 minutes!

I guess he didn't want to leave his lover alone for long!