Kevin Winter/Getty; Stephen Shugerman/Getty
07/19/2007 AT 07:30 AM EDT
Here's a member of Adrian Grenier's entourage who's kept a low profile – Sports Illustrated
swimsuit model Melissa Keller, who sources have identified as his girlfriend.
Grenier has been dating the 28-year-old Keller on and off for two years, according to the sources, but recently they've been more public, PEOPLE reports in its new issue, on sale Friday.
Keller was at the side of the Entourage
star at his 31st birthday party
earlier this month at a Malibu beach house. And on July 14, they cuddled at a Los Angeles bash, where, says an insider, they "seemed oblivious to everyone around them."
Grenier's rep had no comment.