Holly Madison lost her boyfriend.

Hugh Hefner's ex-girlfriend Holly Madison seemed to be making the most of her newfound freedom as she attended Sunday night's 5th Annual Hollywood Style Awards ... but she didn't look so happy to be hanging out with her potential replacement.

Madison showed up to the event alongside one of the busty blonde twins now rumored to be romantically involved with the Playboy founder (although an insider told us that Madison "can't stand" her).

The girls kept to themselves for most of the event and Madison seemed particularly miserable, although she's obviously cashing in on her "Girls Next Door" fame for as long as possible with a string of hosting gigs lined up over the coming weeks.